The 6.0L LQ4/LQ9 in the 2007–2013 Silverado 2500HD/3500HD (and some 1500s) responds well to exhaust upgrades. Whether you want a deeper tone on a daily driver or max flow on a towing rig, here are the best options.
Why Upgrade the Exhaust on the 6.0?
The factory exhaust on the GMT900 6.0L is very quiet and mildly restrictive. Upgrading gives you:
- Better exhaust flow for more power
- More aggressive or deeper exhaust note
- Weight savings with aftermarket systems
Option 1: Flowmaster 40 Series Muffler (Budget-Friendly)
One of the most popular and affordable upgrades. Replace the factory muffler with a Flowmaster 40 Series for a classic American muscle tone without going overboard.
Flowmaster 40 Series Chambered Muffler – 3" Inlet/Outlet – Aggressive tone, great for daily drivers and tow rigs.
Option 2: Borla ATAK or S-Type Cat-Back
For a full cat-back system, Borla makes an excellent stainless steel option for the GMT900 6.0L. The S-Type gives a deep, moderate tone while the ATAK is louder and more aggressive.
Option 3: Single-to-Dual Exhaust Conversion
If your 6.0L came with a single exhaust (common on 2500HD/3500HD), converting to a true dual exhaust is one of the best flow improvements you can make. This involves Y-pipe and dual muffler work.
Expected Power Gains:
- Muffler swap only: 5–10 whp at redline
- Full cat-back: 10–20 whp
- Headers + cat-back: 25–40 whp
Sound Level Guide:
- Flowmaster 40 Series: Moderate-aggressive, minimal interior drone
- Flowmaster Super 44: Louder, more raspy tone
- Borla S-Type: Deep, smooth tone with minimal drone
- Borla ATAK: Very aggressive – better for show trucks
Drone Concern:
The biggest complaint with chambered mufflers on trucks is highway drone at 1,500–2,000 RPM. For long-distance towing trucks, a Borla or MagnaFlow resonator muffler is a better choice.
What exhaust setup are you running on your 6.0 GMT900? Post your experience and sound clips if you have them!