Universal 4" Optimal Flow Muffler

The Universal 4" Optimal Flow Muffler fits any 4" aftermarket straight pipe exhaust system on Powerstroke, Cummins, and Duramax trucks. It's a straight-through, non-directional design built to knock down resonance without choking your flow.

The body is T409 unpolished stainless steel with internal stainless steel mesh and fiberglass, and that straight-through path is what keeps back pressure low while still quieting things down. Both ends run a 4-inch inner diameter on the inlet and outlet. Overall length is 20.25 inches, with a 14-inch body that's 7 inches round.

Because it's non-directional, you can install it in either orientation. To fit it, measure and cut your current exhaust. Welding it in place is recommended, though you can clamp it on instead. Just note that clamps are not included.

It works across all Powerstroke, Cummins, and Duramax models as long as you're running a 4" aftermarket straight pipe setup. Alaska, Hawaii, and some Canadian locations are subject to additional freight charges, which show at checkout based on your address.