The Flow FX series mufflers are for the enthusiast who is looking for an economically priced performance muffler that delivers a moderate sound level and tone, both inside and outside the vehicle. The large straight-through smooth core offers up a different sound than that typical "chambered" sound that Flow master has become famous for. These new mufflers have a compact 4. 00 inch diameter round body that will fit nicely on just about any application and feature a fully welded 409S stainless steel case for increased durability.