Exhaust question Wth is this?

[roadrunner]

It's where the home made turbo used to be...
If you're looking for a cool exhaust design, check out the tesla valve,I'd build one myself if I had the bits laying around.
https://en.wikipedia.org/wiki/File:Tesl ... ection.png

[Racer97]

That is where the .muffler bearings are.