Best LMM EGR Delete Kit: What to Look for Before You Buy

If you own a 2007.5–2010 Chevrolet Silverado or GMC Sierra 2500HD/3500HD with the 6.6L LMM Duramax, you have probably already discovered what every LMM owner eventually learns: the emissions equipment on this engine is its only real weakness.

An EGR delete kit addresses the most immediate threat. This article covers what to look for before you spend a dollar — material quality, kit completeness, the block-off-plate-vs-up-pipe decision, real fuel economy gains, and the installation pitfalls that separate a reliable job from a weekend you will regret.

What Makes the LMM Different

Before comparing kits, you need to understand what makes the LMM unique among Duramax generations.

The LMM launched in mid-2007 as GM’s response to tightening EPA emissions standards. Compared to the revered LBZ it replaced, the LMM received:

• A DPF system with active regeneration — GM’s first. Prone to excessive regen cycles, clogging, and eventual failure. A replacement DPF runs approximately $2,000.

• A significantly larger EGR cooler — To meet the stricter NOx targets, GM had to recirculate substantially more exhaust gas. The larger cooler handles more heat, but at higher mileage it is common for the internal core to crack from thermal cycling, allowing coolant to leak directly into the cylinders.

• A six-hole injector design — The six-hole pattern on the LMM places two spray paths directly above the piston wrist pin, the weakest structural point. This is why stock LMM pistons crack at the 600–650 wheel horsepower range .

There is one bright spot that makes the LMM uniquely attractive among emissions-era Duramax engines: it has no DEF system. DEF — Diesel Exhaust Fluid — was introduced with the LML in 2011. The LMM burns cleaner exhaust through the DPF alone.

The LMM is, mechanically speaking, an extremely reliable engine wrapped around two unreliable emissions components. Delete those components, and you effectively have an LBZ with better heads and bigger injectors.

What an EGR Delete Actually Does

The Working Principle of EGR

EGR stands for Exhaust Gas Recirculation. The system routes a portion of the exhaust stream — soot and all — through a cooler, then back into the intake manifold via the EGR valve. The goal is to lower combustion temperatures enough to reduce NOx formation.

The side effect: every LMM owner is a Y-bridge caked with carbon sludge a quarter-inch thick after 150,000 miles.

An EGR delete kit accomplishes three things:

1. Blocks the exhaust path. A plate seals off the EGR branch on the up pipe (the passenger-side exhaust pipe that feeds the turbo). No exhaust gas reaches the intake.

2. Bypasses the coolant circuit. The EGR cooler was plumbed into the engine’s coolant system. Removing it leaves two open nipples — a coolant bypass hose loops them together to maintain proper coolant pressure and keep your cabin heater working.

3. Eliminates the intake restriction. The factory EGR valve housing and the carbon-clogged intake elbow are replaced with a high-flow pipe. Your turbo now breathes nothing but filtered, oxygen-rich air.

A Tune Is Mandatory

The ECM expects sensor feedback from the EGR valve, temperature probes, and throttle valve. Without a tune that disables these monitors, the truck will illuminate the check engine light immediately and may enter limp mode — on the LMM, the ECM can cut fueling to a crawl once it registers missing EGR sensors.

The Upgrade Worth Considering: Standard Delete vs. Delete + Up Pipe Replacement

There is one standard way to do an LMM EGR delete properly, and one upgrade that makes it permanent.

The Standard Approach: EGR Delete Kit

A proper EGR delete kit includes everything needed to remove the EGR system correctly:

• Billet aluminum intake block-off plates with O-ring seals (for the ports where the EGR valve connected to the intake manifold)
• An exhaust block-off plate with gasket (for the EGR branch on the up pipe)
• A reinforced silicone coolant bypass hose with clamps, and all required hardware

This is the baseline. It eliminates the EGR cooler leak risk, stops carbon sludge from entering the intake, and removes the airflow restriction in the factory intake elbow. For most LMM owners, this is the complete solution.

What about just a blocker plate? 

Some sellers offer a standalone metal plate — no intake block-offs, no coolant bypass, no hardware. It is a temporary band-aid that blocks the EGR port but leaves the EGR cooler hanging in place, the coolant circuit open, and the intake ports unsealed. 

The Upgrade: Delete Kit + Up Pipe Replacement

The LMM up pipe has flex bellows — an accordion-style section designed to absorb thermal expansion. When you block the EGR branch, exhaust pressure that previously had two exit paths (turbo + EGR cooler) now has only one (turbo). This increases stress on the bellows.

eventually those bellows can crack. When they do, you get an exhaust leak, a boost leak, reduced power, and a repeat teardown.

The Fix:

The upgrade that solves this is a replacement passenger-side up pipe with no EGR branch. Because there is no blocked EGR port, there is no concentrated stress point. This is the permanent solution — the same approach a professional diesel shop uses when a customer says “I never want to touch this again.”

The Trade-off: 

You must remove the downpipe to access the up-pipe bolts at the turbo flange, which adds roughly 1–2 hours to the job. But if you are already doing a DPF delete (which requires exhaust work anyway), the incremental labor is minimal.

Which One Should You Buy?

Your Situation	Recommended Solution
Budget-constrained, truck under 150K miles	Standard EGR delete kit — monitor the bellows at oil changes
Truck over 150K miles, original up pipe	Delete + up pipe upgrade — the bellows are already fatigued
Doing DPF delete at the same time	Delete + up pipe upgrade — downpipe is already out
Daily driver, cannot afford repeat labor	Delete + up pipe upgrade — do it once
Weekend warrior, comfortable wrenching	Standard delete kit — you can upgrade later

The honest answer: if you can afford the extra $107, buy the up-pipe upgrade. The money you save on the standard kit evaporates instantly if the bellows crack and you pay for the labor twice.

5 Things to Look for Before Buying Any Kit

1. Material Quality

EGR delete components live in the hottest, most pressure-intensive part of your engine bay. Material shortcuts here become problems within months.

Material	Where Used	Durability	What to Avoid
Billet 6061-T6 aluminum	Intake block-off plates, intake elbow	Excellent — CNC-machined, anodized, resists corrosion	Cast aluminum (porous, can crack under boost cycling)
304 stainless steel	Up pipe, exhaust block-off plate	Excellent — rated for continuous exhaust gas temperatures up to 1,600°F	409 stainless (corrodes faster, thinner gauge)
T409 stainless steel	Up pipe, exhaust flanges	Good — adequate for moderate-duty use, lower cost	Unknown-grade “stainless” from no-name suppliers
Silicone (reinforced)	Coolant bypass hose	Must withstand 250°F+ coolant and vibration	Rubber heater hose not rated for engine bay heat

Laser-cut flanges are a quality signal. A flange that is waterjet or laser-cut mates flat against the gasket surface with even pressure. Stamped or rough-cut flanges create uneven sealing surfaces — and an exhaust leak at the up-pipe flange is a miserable thing to fix after the truck is back together.

2. Kit Completeness

Open the box before you turn a single wrench. A complete LMM EGR delete kit should include:

• Intake block-off plates — two plates with O-ring grooves, for the ports where the EGR valve connected to the intake manifold
• Exhaust block-off plate — for sealing the EGR branch on the up pipe, with gasket
• Coolant bypass hose or tube — U-shaped, silicone or reinforced, with clamps
• Hardware — Grade 8 or 10.9 bolts, washers, and nuts that match the kit’s mounting pattern
• Gaskets — at minimum, a gasket for the exhaust block-off plate; some kits include intake gaskets
• Intake support bracket — prevents the intake elbow from vibrating loose (a common cause of post-install boost leaks)

If the kit arrives without gaskets or with generic hardware-store bolts, return it. Reusing 15-year-old factory gaskets on a component that sees 30+ PSI of boost pressure is a leak waiting to happen.

3. Year-Specific Fitment

Not all LMM trucks are identical. Verify:

• Standard pickup vs. Cab & Chassis: EGR delete hardware designed for a standard 2500HD/3500HD pickup will not fit a Cab & Chassis commercial truck. The frame, engine mounting position, and exhaust routing differ.
• 2007.5 cutoff: Early 2007 trucks are LBZ engines (no DPF, smaller EGR cooler). Late 2007 trucks are LMM engines. The EGR delete kit is not interchangeable between the two.
• Transmission type: The Allison 1000 automatic is standard on all LMM trucks. Manual-transmission LMMs are exceptionally rare but do exist — confirm kit compatibility if applicable.

4. Tuning Is Mandatory, Not Optional

The factory calibration will detect the missing EGR valve, EGR temperature sensors, and throttle valve position within seconds of startup. The result is a check engine light at minimum, and limp mode — which on the LMM limits engine output to approximately 30 MPH — at worst.

The LMM’s EGR And DPF Systems Are Interconnected

If you delete the EGR but leave the DPF in place, the DPF still loads with soot, still runs active regeneration cycles, and still eventually plugs with non-burnable ash. The ideal path is to address both systems together. But if budget forces a choice, delete the EGR first — it stops carbon sludge from entering the engine. The DPF delete follows for power and fuel economy.

5. Consider a PCV Reroute at the Same Time

While the intake is apart, rerouting the PCV (Positive Crankcase Ventilation) system is a $80 job that takes 30 minutes and pays dividends for the life of the truck.

The factory PCV system routes crankcase vapors — oil mist, blow-by gases — directly into the turbo inlet. Before the EGR delete, this oil vapor mixed with soot from the EGR to form the carbon sludge coating your Y-bridge. After the delete, there is no soot to mix with, but the oil vapor still coats the compressor wheel, intercooler, and intake boots. Over time, this degrades intercooler efficiency and can cause turbo compressor wheel pitting.

TruckTok Product Recommendations

TruckTok offers two LMM EGR delete solutions that cover both approaches discussed above.

2007-2010 6.6L Chevy GMC LMM Duramax EGR Valve Cooler Delete Kit

This is the standard EGR delete kit — the complete solution that eliminates the EGR system for the lowest possible cost.

What you get: CNC-machined billet aluminum block-off plates with anodized black finish, a reinforced silicone U-shaped coolant bypass hose with clamps, and all required hardware. 

Why it makes sense: At $61.99 with free shipping, this kit eliminates the immediate threats

• EGR cooler will not crack into the cylinders,
• carbon sludge will not build in the intake
• The airflow will not restriction in the intake elbow.
  
• LMM owners can complete this job in 3–4 hours with basic hand tools.

What to know: This kit retains the factory up pipe with its flex bellows. As discussed above, the bellows will eventually fatigue under the additional backpressure of a blocked EGR branch. Most owners report this happening at the 50,000–80,000 mile mark post-delete — not immediately, but eventually.

📖 Step-by-step install guide: TruckTok Forum — LMM EGR Valve & Cooler Delete Kit Installation

2007.5-2010 6.6L Duramax LMM Passenger Up Pipe & EGR Delete Kit

This is the EGR & Up Pipe solution — the same approach a professional diesel shop uses when a customer wants the EGR system gone permanently.

What you get: A stainless steel passenger-side up pipe with no EGR branch, billet aluminum intake block-off plates with O-ring seals, an exhaust block-off plate, all required gaskets, a coolant tube and an intake support bracket to prevent vibration-induced boost leaks. 

Why it is the better long-term investment: 

• By replacing the up pipe entirely, you eliminate the flex-bellows failure point — the one long-term weakness of a standard EGR delete. 
• There is no blocked port to concentrate stress, no gasket that can blow out, no boost leak that develops 50 miles after the install.
• The pipe bolts directly to the exhaust manifold and turbo pedestal using factory mounting points .

What the extra $107 buys you: A delete that you do once. For the cost of roughly two tanks of diesel, you avoid the possibility of a repeat teardown when (not if) the factory bellows crack under the blocked EGR branch.

📖 Step-by-step install guide: TruckTok Forum — LMM Up Pipe & EGR Delete Kit Installation

Real Fuel Economy: What LMM Owners Actually See

The fuel economy question comes up in every EGR delete discussion. Here are real numbers from an LMM owner who tracked every fuel receipt over 40 days before and after his delete.

Metric	Before Delete	After Delete
City MPG	5–10 (EGR actively failing)	20–25
Highway MPG	Not recorded	18–22
Best observed	—	30 MPG (city, optimal conditions)
Days between fill-ups	6.8	8.8
Fill-ups per 40-day period	7	6

The 30 MPG city figure is a best-observed number, not a steady-state average — but the fact that a 7,000-pound truck with a 6.6L diesel can touch 30 MPG at all after a delete is something no factory-emissions Duramax will ever see.

The Mechanism Is Straightforward: 

deleting the EGR removes the intake restriction (carbon sludge and hot, oxygen-depleted exhaust gas diluting the intake charge), and deleting the DPF eliminates regeneration cycles that inject raw diesel into the exhaust stroke to burn off trapped soot. Cleaner air in, less fuel wasted — it is not magic, just better combustion.

Installation Overview

An LMM EGR delete is a 3–5 hour job for a competent DIY mechanic — longer if you are replacing the up pipe, which adds downpipe removal to the task list.

Before starting:

• Disconnect both batteries
• Let the engine cool completely
• Drain 1–2 gallons of coolant. The LMM has no radiator petcock — drain by pulling the lower radiator hose at the passenger-side fender well
• Dry-fit the block-off plate against the up-pipe flange before you turn a single bolt. Confirm mounting holes line up

Tools you need beyond basic sockets:

• 12-point 12mm socket — up-pipe bolts at the turbo and exhaust manifold are 12-point. A 6-point socket will strip the bolt heads
• Penetrating oil — soak the up-pipe bolts for at least 30 minutes. These bolts have survived 15 years of heat cycling and will snap if forced dry
• Long-handle 3/8" ratchet or cheater pipe — the up-pipe bolts are tight enough that a standard ratchet may not break them loose
• Stubby 12mm wrench — for the rear EGR cooler bolt, which lives in a gap too narrow for a full-size wrench
• Copper anti-seize — apply to every bolt thread going back in, especially up-pipe bolts, so the next removal is not a fight

General installation sequence:

1. Remove intake tubing, airbox, PCV piping, and turbo intake horn to clear workspace

2. Unplug EGR valve, temperature sensors, and coolant level sensor. Tape and zip-tie unused connectors — do not cut them

3. Remove the EGR valve from the intake manifold

4. Cut the EGR cooler coolant hoses — they are nearly impossible to remove intact, and you are replacing them anyway. Expect coolant spillage

5. Unbolt the EGR cooler: two 14mm bolts at the front, one 12mm at the top rear, two 12mm from the back side. The rear upper bolt requires a stubby wrench and a pry bar — wedge, pry upward, then spin by hand

6. If replacing the up pipe: Remove the downpipe (turbo heat shield off, V-band clamp at turbo outlet, transmission dipstick bracket loosened, pipe out through the wheel well — removing the passenger front wheel and inner fender liner helps significantly)

7. Unbolt the up pipe: three 12-point 12mm bolts at the turbo flange, three at the exhaust manifold. If manifold bolts resist, apply heat with a torch before forcing them. If a bolt starts to tighten as you back it out, stop — spray penetrating oil on the exposed threads, thread it back in, then back it out again. This is how you avoid snapping a bolt in the turbo flange, which means pulling the turbo to drill and tap it

8. Install the block-off plate OR replacement up pipe with copper anti-seize on every bolt thread

9. Route the coolant bypass hose from the front port to the firewall-side port

10. Install the high-flow intake elbow. If the kit uses an O-ring seal, clean both mating surfaces thoroughly — debris under that O-ring becomes a boost leak under load

11. Reinstall turbo intake horn, PCV piping, airbox, and intake tubing

12. Refill coolant, bleed air via the bleeder screw on the thermostat housing

13. Flash the ECM tune before starting the engine

After the Install: Three Things That Go Wrong

You finish the install, flash the tune, and take the truck out. Everything is fine — until 50 miles later when you hear a hissing noise under load. This is common enough that it deserves its own section.

1. Boost Leak at the Intake Elbow

If you hear a hissing or turbo whistle that was not there on the first drive, check the intake elbow first. Most budget kits use an O-ring seal at the Y-bridge connection. If the mounting bracket bolts are even slightly loose, engine vibration works the elbow back and forth until the O-ring loses its seal — and you get a boost leak that sounds like a bad turbo and drops power.

The Fix: 

Tighten every bolt on the intake elbow bracket. If the kit’s mounting holes did not line up and you forced it, the O-ring is already compromised — pull it, inspect it, and use a thin bead of high-temp copper RTV on the mating surface as insurance. A kit with an intake support bracket (like TruckTok’s up-pipe kit) is designed to prevent this exact failure mode.

2. Exhaust Leak at the Block-Off Plate

The exhaust block-off plate seals the EGR branch on the factory up pipe. This plate-and-gasket stack can develop a leak over time — the factory gasket was designed for the EGR cooler flange, not a flat plate, and exhaust pressure can find its way through if the seal is imperfect.

The Fix: 

Check for soot traces around the plate. If leaking, remove the plate, clean both surfaces to bare metal, and reinstall with high-temp exhaust sealant on both sides of the gasket. If the leak persists, the flex bellows in the up pipe have cracked from the increased backpressure — this is the long-term failure mode of retaining the factory up pipe. The permanent fix is upgrading to a replacement up pipe with no EGR branch, like TruckTok’s $169.36 up-pipe kit.

3. Loose Coolant Bypass Hose

The coolant bypass hose connects two hard-to-reach nipples — one at the front of the engine, one near the firewall. The spring clamps included in some kits do not hold tension well after heat cycling.

The Fix: 

Replace spring clamps with stainless worm-gear clamps. Check this connection again after the first week of driving — a slow coolant drip at the firewall side is hard to spot but easy to fix.

Conclusion

The LMM Duramax is a fundamentally solid engine saddled with emissions equipment from GM’s first attempt at meeting EPA diesel standards. The EGR cooler cracks and dumps coolant into the cylinders. The DPF clogs and runs excessive regeneration cycles. The six-hole injector design adds heat to an already vulnerable piston wrist pin.

An EGR delete kit stops the most immediate threat — carbon sludge in the intake and coolant in the combustion chamber.

• For the budget-conscious owner who wants the EGR system gone at the lowest cost, the LMM EGR Valve & Cooler Delete Kit at $61.99 is the complete standard solution. It eliminates the EGR cooler leak risk, stops the intake contamination cycle, and installs in an afternoon.

• For the owner who wants to do this once and never touch it again, the LMM Up Pipe & EGR Delete Kit at $169.36 upgrades the standard delete with a stainless steel up pipe — no bellows to crack, no block-off plate to leak, no repeat teardown.

Both kits ship free from TruckTok. Both include step-by-step installation guides on the TruckTok Forum. And both do the same essential thing: they give your LMM the intake tract it should have had from the factory — nothing but clean, cool, filtered air.

FAQ About Best LMM EGR Delete Kit

Q1: Do I need a tuner before I install the EGR delete kit? 

A1: Yes — flash the tune before you start the engine. The ECM will detect missing EGR sensors within seconds and can force limp mode, limiting the truck to roughly 30 MPH. Start the physical work only after confirming the tune is loaded and no error codes are present.

Q2: Can I run the EGR delete with the factory exhaust? 

A2: Yes, but the DPF becomes the bottleneck. Without EGR dilution of combustion temperatures, the engine produces slightly more soot that loads into the DPF faster. The DPF will survive for a while but eventually plugs — a replacement costs roughly $2,000. 

Q3: Will an EGR delete cause my truck to smoke? 

A3: You may see slightly more visible exhaust at cold start — that is unburned fuel vapor the EGR previously recirculated, and it is normal. Under driving conditions, a properly tuned LMM should run clean. Black smoke under load means the tune is over-fueling, which is a tuning issue, not a function of the delete itself.

Q4: Does the LMM EGR delete require removing the intake manifold? 

A4: No. Unlike the LLY — which requires pulling the Y-bridge for EGR work — the LMM’s EGR system is mounted on the passenger side, higher and further back. The intake manifold and Y-bridge stay in place. Clearance near the firewall is tight, but the job does not involve a top-end teardown.

Q5: Is an EGR delete legal? 

A5: Removing factory emissions equipment violates the federal Clean Air Act and is illegal for on-road vehicles in all 50 states. Kits are sold for off-road and competition use only. States with mandatory emissions testing — notably California under CARB — actively enforce compliance. Know your local laws before purchasing.

Q6: How long does the install actually take? 

A6: Plan on 3–5 hours for the standard delete, or 5–7 hours if you are replacing the up pipe too. First-timers should budget a full weekend — tight clearance at the firewall and the risk of seized bolts make this a job where rushing leads to broken parts.

Q7: Can I undo the delete if I need to sell the truck or pass emissions? 

A8: Yes, if you saved the factory parts and disconnected connectors rather than cutting wires. Reinstallation labor is roughly the same as the original job, and you must reflash the ECM to factory calibration.

Q7: What happens if I delete the EGR but keep the DPF? 

A8: The engine runs, but the DPF loads with soot faster because there is no EGR dilution of combustion temperatures. Active regeneration cycles still occur, dumping raw diesel into the exhaust stroke to burn off soot. Over tens of thousands of miles, non-burnable ash accumulates and the DPF eventually plugs.

Q9: Will an EGR delete improve towing performance? 

A9: Yes, in three ways. EGTs drop 150–200°F — critical when pulling a grade under load. The turbo spools faster without the carbon-clogged EGR valve and intake elbow restricting airflow. Towing fuel economy typically improves from 8–10 MPG to 12–15 MPG after the delete.

Q10: Should I do a PCV reroute at the same time as the EGR delete? 

A10: Not mandatory, but strongly recommended while the intake is already apart. The factory PCV system vents oil vapor into the turbo inlet — without EGR soot to mix with, that oil still coats the compressor wheel, intercooler, and intake boots over time.