Hi guys,

I have a Revhard 2.5" downpipe and a OEM GSR cat. I was wondering if there is anyway at all to get a 2.5" DP flange to bolt up to the front end of the OEM GSR cat without getting a leak or something.

I'm guessing that it's not possible, so I might end up having to get a 2.25" flange mounted to the aft end of the 2.5" DP. Which brings me to my next question. Can a 2.5" pipe be welded to a 2.25" flange?

I guess if the 2.5" WG pipe cant be welded to the 2.25" flange I'd have to get a 2.5" to 2.25" transition pipe. But before I get a reducer I wanted to know if I can at least have a 2.5" DP, so when I eventually upgrade the rest of my exhaust system to 2.5" or 3" I wont have to modify my DP again.

Thanks

 

If you dont want to mess with the DP later, just weld the 2.5 flange to the DP. Then weld a 2.5 flange to a reducer going to the cat.

 

Yah that could work...I was looking at the burns site, and I was wondering if I should go with a long transition or a short one.

I'm looking at http://www.burnsstainless.com and I'm trying to calculate the length of the 2.25" to 2.5". Part number RD-225 has a 2.25" small end and a 3" big end. Burns says to find the length subtract the small end from the big end that I want, and multiply the length difference by either 4.07 for the long transition pipe or 1.87 for the short transition pipe.

So if I get a long 2.25" to 3" transition pipe it would be 1" long from the 2.25" to the 2.5 end.

If I went with the short 2.25" to 3" transition pipe it would be a little under half an inch long.

If my calculations are correct the overall length of the 2.25" to 3" long pipe is 3.05" long and the 2.25 to 3" shortpipe is 1.4" long.

So I guess go with the 2.25" to 3" long transition pipe and cut of a little on the large end until the opening is 2.5".