Ok now don't get mad at this stupid question. If you get an after market downpipe (perrin) and a catback exhaust (cobb tuning) do they bolt directly to each other or is there something in between them?

 

Some bolt directly, some don't. Some systems have a midpipe as well, like the stock system. Go for the aftermarket dp that replaces both stock dp and midpipe with one pipe. Then slap that sucka to a catback.

 

helix DP

 

http://www.mrtrally.com.au/performan..._underskin.htm

Uppipe just above (3 o'clock) the tire:


DP coming down from Turbo:


Here you can see the exhaust side of the turbo (the big rusty hole) where the DP is attached:


Take a look at these pics. The exhaust manifold is attached to the uppipe. The uppipe is attached to your turbo, it feeds the turbo your exhaust. The exhaust is then fed to your dp.