Originally Posted by Tom@Rennsport-1

I'm sorry but this is not true at all. Many aftermarket companies, such as Cargraphic, AWE, Tubi (just to name a few) all make their mufflers entirely in-house. I know because I've seen their production facilities in person.

The benefit is that they then have the ability to not only tailor the sound of their mufflers, but also to insure that they provide maximum performance at the same time.