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★★★★★ 4.8 / 5
from 10,000+ verified diesel owners
2011-2015.5 Chevy/GMC 6.6L Duramax LML Turbo Diesel 3Inch Downpipe Exhaust
$268.50
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Ships today from our nearest US warehouse.
Backed by our 100% money-back
FITMENT
- 2011-2015.5 6.6L Silverado &Sierra Duramax 2500HD/3500HD with LML Diesel engine pickup.
- This downpipe features a V-Band connection flange at the turbo outlet.
- NOT directly fit 2015.5-2016 models with the 3-bolt flange exhaust system unless the downstream system is modified.
DESCRIPTION
Product Overview
-
The factory downpipe on 11-15.5 Duramax LML trucks is a major performance bottleneck. To squeeze past tight engine bay clearances, GM engineers severely crushed and flattened the stock pipe.
- This restricted "pancake" design chokes exhaust flow, traps excessive thermal energy right at the turbo charger, and spikes EGTs under heavy towing loads.
- Upgrading to smooth, 3-inch mandrel-bent downpipe maximizes exhaust flow right from the turbo outlet, rapidly dropping EGTs and allowing the turbo to spool up much faster.
Key Features
- Heavy-Duty Wrapped Protection: Crafted from high-grade 304 stainless steel and wrapped in premium heat-insulating sleeve to safeguard surrounding engine bay components.
- TIG-Welded Construction: All joints are precision TIG welded and jig-built to prevent cracking under high thermal cycling and aggressive vibration.
- Unrestricted 3" Bore: Replaces the restrictive, "crushed" factory oval pipe with a true, consistent 3“ mandrel-bent round diameter through every turn.
- Drastic EGT Reduction: Smooths out exhaust flow to quickly draw extreme heat away from the turbo, reducing under-hood temperatures and protecting engine health.
FAQ
Q: Will this fit my 2015 or 2016 model?
A: It fits 11-15.5 models that use a V-band style turbo connection. In 15.5-16, GM switched the LML to a 3-bolt flange style downpipe. Please inspect your truck's connection before buying.
Q: Does this pipe have the necessary sensor ports?
A: Yes. Unlike older generations, the LML downpipe requires sensor ports. This downpipe is precision-engineered with 3 factory-location bungs to house your stock EGT sensor, NOx sensor, and 9th injector dosing valve flawlessly.
Q: What happens to the sensor bungs if I delete my truck?
A: If you are doing an emissions delete and removing these sensors, you must buy a standard LML downpipe plug kit (or sourcing matching bolts/plugs) to cap the 3 bungs off so exhaust gas doesn't leak out.
Q: Will this 3" downpipe work with my stock exhaust or an aftermarket 4"/5" delete pipe?
A: Yes, it fits both perfectly. The OEM-matched flanges bolt directly to the stock turbo and factory exhaust. If you upgrade to a 4" or 5" delete pipe, it still fits flawlessly—all downpipe-back systems neck down to bolt directly to this factory location without adapters.
Built by diesel guysTrusted by diesel guys
Derek W.
Verified buyerRunning between three rig sites every week, was burning through DEF in about 2 weeks. Getting 6 weeks per jug now. Regen lockouts used to cost me half a day in the field, that's done with.
Chris D.
Verified buyerGot four trucks on the ranch, did this one first to see how it'd go. Eight months in, no codes, pulls hay like she's new again. Other three are getting done before winter.
Travis M.
Verified buyerTowing the boat down to the Keys used to kill me at 11 mpg. Got 15.4 last trip, same boat, same route. Pipe looks stock from the outside, none of my buddies even noticed it's gone.
Mike R.
Verified buyerHauled my horses from Fort Worth up to Amarillo last month, got 17.8 empty on the way back. Was running around 13 before. Pulls a lot better up the grades too, didn't expect that part.
Jason T.
Verified buyerUsed to go into regen every 280 miles when I was loaded down, now I'm pushing 580 with no regen at all. EGTs run way cooler too pulling the skid steer. Wish I had done this sooner, honestly.
Brandon L.
Verified buyerBought it used and the previous guy had wiped the delete history clean. Got everything put back the right way, ran the protocol, passed smog first try. Truck finally drives like it should.
Trusted by 10,000+ american diesel owners
2011-2015.5 Chevy/GMC 6.6L Duramax LML Turbo Diesel 3Inch Downpipe Exhaust
Ford 6.7 Powerstroke Full Delete Bundle (2020-2022) The complete kit to unlock your 6.7 Powerstroke from factory emissions restrictions. Eliminates the DPF, EGR, and the expensive failure points that come with them - regen cycles, clogged filters, sensor failures, and the dealer quotes that follow.
Guaranteed Fitment
American Owned
24/7 US Support
Free USA Shipping
Every Bundle Includes
Delete Pipe Hardware Kit
American-fabricated stainless. Fitment-specific.
Custom
ECU Tune
Calibrated for your engine, your truck, your driving style.
EZ Lynk or HP
Tuners Programmer
Plug-and-flash. Step-by-step instructions included.
Step-by-step
Install Video
Watch our techs do it. DIY in
2 to 4 hours.
24/7 US-based
Mechanic Support
Real diesel techs on the line. Not a chatbot.
Guaranteed Fitment or Money Back
VIN-verified. If it doesn't fit, you're covered.
Install it in your driveway
1
Unbox & inspect
15 min
2
Flash ECU & verify
20 min
3
Remove stock components
60 - 90 min
4
Install hardware kit
45 - 60 min
TRUE AMERICAN DIESELVS.OTHER RETAILERS
THEM
24/7 access to a real mechanic - not a chatbot or ticket queue
Support hidden behind contact forms and multi-day email replies
Guaranteed Fitment Or Your Money Back - every kit, every truck
Compatibility warnings buried in fine print, after you've already paid
5,000+ verified reviews, sorted by your exact engine platform
One generic review count for every truck on the site
Proven 5–8 MPG gain - real dyno results, not a marketing guess
Vague performance claims with no data behind them
Lifetime warranty, spelled out in plain terms - no fine print maze
Vague "we'll fix it" warranty language, no stated terms
Recently Viewed
The TAD Crew
Fort Worth HQ. Warehouses in California, Kentucky & Florida. Real American mechanics build your kit. A real American picks up the phone. No call center. No script. No chatbot.
4US Shops
10,000+Trucks Restored
+5–8MPG Gain
24/7US Mechanic Support
Fort Worth · CA · KY · FL
Real US phone line
Reversible install
Fitment guaranteed or refundGot questions?
The stuff that keeps you up at night before you commit. Answered in plain talk by guys who actually wrench on these trucks.
A full mandrel-bent stainless DPF and CAT delete pipe, EGR block-off plates and gaskets, DEF delete components, all mounting hardware and clamps, and your preloaded tuner with the custom tune for your VIN. We don't ship anything you don't need, and we don't leave anything out that you do.
No. The custom tune disables the codes the deleted hardware would otherwise throw. Dash stays clean. If a real fault code pops up after install, call our line and a tech walks you through it. Usually it's a sensor that got unplugged during the wrench work, takes 5 minutes to sort out.
We pull your VIN before we ship. Engine, year, trim, cab config, all verified against the kit. If it doesn't fit your truck, you send it back and we either ship the right kit or refund you in full. Fitment is on us, not you. That's why we call it a fitment guarantee.
Most of our customers do. Average install is 2 to 4 hours with basic hand tools, sockets, ratchet, jack stands. You'll get the step-by-step install video emailed after purchase and a 24/7 phone line if you get stuck. If you can change your own oil, you can run our protocol.
Real custom files. Built in-house by guys who've been turning wrenches and writing tunes on Cummins, Duramax, and Powerstroke platforms for years. Every tune is dialed to your year, your engine, and how you actually drive the truck. No outsourced generic tunes pulled off a shared drive.
Once we've got the base files for your platform, dialing it in for your specific truck takes about 20 minutes. Charging $300 for that didn't sit right with us. We'd rather give you the better experience and earn the call when your buddy's truck needs help.
You call us. Real diesel techs, US-based, picking up the phone. We help with install troubleshooting, tune adjustments, fitment issues, codes, anything. We don't disappear after the sale, and the line doesn't go to voicemail. Phone number is at the bottom of every email and on every page of this site.
Yes. The custom tune is reversible, flash the stock file back through your tuner and the truck reads as factory again. The only thing that's permanent is the deleted hardware itself, but most buyers in the diesel community see a properly executed delete as a value-add, not a deduction. We can also ship the OEM-style reverse plates if you want to put the factory exhaust back on for resale.
Lifetime warranty on the stainless delete pipe, no rust-through, no cracks, ever. 2-year warranty on the EGR delete plates, gaskets, and hardware. If anything fails, we ship a replacement same day. The tuner itself carries the manufacturer warranty through EZ Lynk or HP Tuners.
Orders ship from Fort Worth within 1 to 2 business days. Free express shipping anywhere in the lower 48. Most orders land in 3 to 5 days. You'll get tracking the second it leaves the shop.
