4"/5" Downpipe-Back 2011-2015 LML 6.6 Duramax DPF Delete Race Pipe | SPELAB

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Unlock your 2011-2015 LML Cummins's true potential with this high-performance DPF delete pipe. Our precision-engineered solution eliminates restrictive factory filters, dramatically reducing exhaust gas temperatures (EGTs) while improving turbo spool-up and throttle response. The mandrel-bent construction ensures maximum flow efficiency, helping your diesel breathe easier. Perfect for off-road enthusiasts seeking better power delivery and reduced maintenance hassles.

Specification

Benefits

Expect to see a significant increase in fuel mileage. If your DPF is plugged up your probably averaging about 13-14 mpg. More or less depending on the severity of the restriction. After deleting the DPF/CAT expect to get a combined mileage of 18-19 mpg.

• It removes the need to service the DPF at regular intervals (cleaning, replacement)
• A DPF delete will remove the possibility of a DPF failure which could cause expensive diesel repairs
• Due to less exhaust backpressure, the DPF delete increases exhaust flow and therefore increases the performance of your motor!
• Paired with an ECU remap, the DPF delete is proven to increase power and torque for all vehicles

Installation

Install takes about 1hr with basic hand tools done on the ground of your driveway or garage. Quicker if you have automotive style lift. Cutting may be be required to fit shorter wheelbase bed/cab configurations. Clamps, hangers and hardware are included. You may have to re-use some factory hardware.
Tuner Required: Removal of the DPF, CAT, SCR, and/or DOC involves removing and eliminating emission related sensors. A DPF delete capable tuner is required to prevent any check engine light or diagnostic trouble codes from setting.

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2011-2025 Chevy / GMC Duramax Diesel LML. Silverado and Sierra pickup trucks. 

2015 or 2015.5? 

2015 is a split year. The 2011-2015 downpipe is secured to the turbo-direct pipe using a V-band style clamp. The 2015.5-2016 uses a 3 bolt flange style connection. Be sure to visually verify the clamp style your truck is equipped with.

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Q1. What’s the difference between 4" and 5" exhaust systems?

• 4" – Better for mild/moderate tunes, retains some backpressure for low-end torque.
• 5" – Best for high-horsepower builds, maximizes flow for reduced EGTs and top-end power.

Q2. Will a magnet stick to this pipe? Is it really stainless steel?

Yes – This pipe uses T-409 stainless steel, which is still magnetic (unlike T-304). It offers excellent corrosion resistance while being more affordable than T-304.

Q3. How thick is the pipe? Will it last?

2mm thick T-409 stainless steel – Durable enough for long-term use without excessive weight.

Q4. Is this a full turbo-back or just downpipe-back?

• Downpipe-Back – Replaces everything after the downpipe (DPF & exhaust).
• For a full turbo-back system, you’ll need an additional DPF-delete downpipe.

Q5. Will this improve performance?

• Yes! Benefits include:
• Lower EGTs (Exhaust Gas Temperatures)
• Faster turbo spool
• Better fuel efficiency (with proper tuning)
• No more DPF clogging issues

Q6. Is this street legal?

⚠ Off-Road Use Only – DPF removal is illegal for on-road vehicles in most regions. For competition/racing use only.

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