Down pipe question

[05gtlimited300]

would a short downpipe and perrin rear section fit together? I cant find pics or info that would help. Also does the shorty downpipe eliminate the cat?

[IwannaSportSedan]

A shorty down pipe and a cat back replaces everything behind the turbo EXCEPT the third catalyst pipe. That is the only pipe that doesn't get replaced in your scenario. The shorty down pipe and the cat-back pipes won't fit together in the sense that they don't touch each other.

 

They should be useable together, on the front and back of the catalyst pipe. You can re-use the donut gasket between the catalyst midpipe and the cat-back pipes, or a muffler shop may be able to cut of the existing flange, expand the mid-pipe to meet the cat-back pipes, with a same-size flange and gasket.

 

Going from the stock mid-pipe (~2.5" diameter) to a 3" cat-back is not great for just a flat-gasket, as there is not much overlap on those flanges. The donut gasket works, but can be less than easy to deal with and get sealed correctly.

 

My Cat-back is going back in to have the catalyst midpipe expanded for a new 3" gasket to meet the cat-back flange soon. It works now with a barely-overlapped flat gasket, but a new 3" flange on the catalyst pipe will work better.

 

A long down pipe and a catback would be considered a "turbo-back" and leave no OE pieces after the turbocharger.