I was wondering if I could keep my stock downpipe and stock cat back and just replace the cat with a test pipe?

I searched the forums and I believe I can it just wasn't stated directly anywhere from what I could find. I believe the stock exhaust size is 2.25" and the test pipe is 3" so I am concerned with the 3/4 difference and possibly a leak. I think this is possible because people just replace the cat back and bolt onto the stock cat.

Here is the test pipe I am interested in:
http://cgi.ebay.com/ebaymotors/MITSU...Q5fCarQ5fParts

I will eventually be doing a 3" cat back, and a 3" downpipe, but for now I just want to be able to log a wb02, and since the stock cat can throw off these readings, I need a test pipe.

Thanks,

 

i did it, took out stock cat and replaced with the megan resonated test pipe, no issue with it
you would also need to space out the second o2 with the fouler so as not to throw a code

 

Thanks for your reply. I ended up getting the megan test pipe as well so thats good news. I'm just going to flash the ecu to fake the cat o2 and use that bung for the wb02.

 

good deal, however I needed to replace the gaskets that came with the megan because of the stock vs 3" since the megan didn't seal as the 2 surfaces did not totally mesh

i used a crush type gasket I got from amazon, can't remember the name, ahh remlfex was what i used

shouldn't the wb be closer up rather than so much further down? I actually used the bung on the megan pipe