Connecting 3" downpipe to cat back exhaust

[monteperformanc]

I recently bought an RJC 3" downpipe. It comes with a 3" test pipe. The test pipe is a 3" round pipe, and the cat back (pypes) exhaust I have is an oval shape which looks smaller. How does this mate up properly? Does everyone just bolt this together like this? I feel it could be a major flow restriction. Feel like I'm missing something here? Also where do I get a gasket for this?

 

[monteperformanc]

Top pic is the RJC test pipe, bottom pic is a stock type test pipe which shows the shape of the exhaust flange.

 

[mikestertwo]

Most test pipes are made to mate up to a 2-1/2" exhaust. You don't use a gasket on the flange.

 

[1984 t-type]

I have the exact same setup as you , RJC pipe and Pypes cat back. I was wondering the same thing but just hooked it up and it seems ok, guess there's really no way to tell if it's a actual restriction or not. I also did not use the flange gasket but only because I lost it, don't think it leaks but I want to replace it.

 

[BuickMike]

Like others said, no gasket needed. If I were you, I would make a paper template of the RJC test pipe and place it up against the catback to see if there is any shrouding going on. If the catback side is covering some of the hole, I would be concerned.

 

[vader87]

Bison posted this up on FB. I have the same issue going from a 3.5 pipe to a 2.5 exhaust. I contacted TA Performance and I am waiting to see if they were able to get me a flange that comes on their test pipe. I will need to have my collector custom made.