RRE Downpipes match to stock cat?

[Justin_Bailey]

Does anyone know if their downpipes mate up to a stock cat? I read they are 2.5 inches before the flex section and then 3" after. So I was wondering if anyone had one of these or similar.

 

[Kevin Jewer]

I've used RRE downpipes a couple times (love them), they use a full 2" Apexi style flange. I don't think this will bolt to a stock cat, but I've never tried it. I've heard a 2.5" flange can be modified to bolt up, but never a 3".

 

[fourreGsixty3]

Is it just me or does buying a DP and keeping the stock cat on sound useless? It doesnt matter if the DP is better flowing, the purpose of getting it will be defeated since the stock cat will restrict the rest of the set-up, if you do this I would go 3" cat with the rest of the system being 3"s.

Dustin

 

[DGajre777]

Is it just me or does buying a DP and keeping the stock cat on sound useless? It doesnt matter if the DP is better flowing, the purpose of getting it will be defeated since the stock cat will restrict the rest of the set-up, if you do this I would go 3" cat with the rest of the system being 3"s.

Dustin

What ^^^ said. Just get their 3" cat with their downpipe.

 

[daren_p]

Is it just me or does buying a DP and keeping the stock cat on sound useless? It doesnt matter if the DP is better flowing, the purpose of getting it will be defeated since the stock cat will restrict the rest of the set-up, if you do this I would go 3" cat with the rest of the system being 3"s.

Dustin

Maybe he needs/wants to put the stock cat in for emissions testing, or is still saving up for an aftermarket highflow cat & this is just temporary? Either way, I run the RRE DP & while I have never tried to hook it up to the stock cat, like 95gsxracer said, I don't think it will work as the flange is more then likely just to large on the DP and too small on the cat as far as bolt spaceing goes. I don't know, maybe there is enough diameter on the stock cat flange to completely slot it out?

 

[Justin_Bailey]

yes, actually I was gonna keep the cat on for emissions testing and add an electronic cutout onto the downpipe. I've never passed emissions with my high flow cat on my other car so I just wanna save the $$$$ I don't have and leave the stock one on this one. California laws suck so I have to go incognito...

 

[daren_p]

yes, actually I was gonna keep the cat on for emissions testing and add an electronic cutout onto the downpipe. I've never passed emissions with my flow cat on my other car so I just wanna save the $$$$ I don't have and leave the stock one on this one. California laws suck so I have to go incognito...

Not sure what the limits are in Cali, but they are fairly strict here & my last emissions test I was no wears close to the limits with my 3" High flow cat. I bought my cat from RRE to match up to their downpipe. May just be a bad tune on the other car or didn't get the cat good and hot before the test?

 

[DGajre777]

yes, actually I was gonna keep the cat on for emissions testing and add an electronic cutout onto the downpipe. I've never passed emissions with my flow cat on my other car so I just wanna save the $$$$ I don't have and leave the stock one on this one. California laws suck so I have to go incognito...

How often is the testing? If it is once or twice a year you could just keep your stock downpipe and cat for emissions testing and then use the RRE long downpipe when you are done with the testing.

Another option is to get their short downpipe with 2 test pipes. You could leave one alone and have the stock cat welded in the test pipe and some adapters. Then just swap the open test pipe with the welded cat one whenever you need to go for emissions testing.

 

[Justin_Bailey]

Kinda complicated here in California. I live in a Fremont and these guys got the worst reputation in all of Cali. for bustin all aftermarket lookin cars. First if the police even see an aftermarket muffler you can get popped.. that happened to me... or if they hear it and it sounds a bit "illegal", you can get popped.. that also happened to me. 2 times to the state ref. is no fun. I figure the safest thing to do here is to run a dp with a cutout and stock catback so I can have the power when I need it and still be able to run around with a quiet exhaust when I don't. Plus if you're like me, I don't wanna mess with my exhaust every other year. It just becomes a p.i.t.a. Smog stations never look under my car in all the years I've gone so why would they on a stock sounding car with stock catback? Just wanted to experiment.. whattdya think?

 

[Justin_Bailey]

Not sure what the limits are in Cali, but they are fairly strict here & my last emissions test I was no wears close to the limits with my 3" High flow cat. I bought my cat from RRE to match up to their downpipe. May just be a bad tune on the other car or didn't get the cat good and hot before the test?

I had a full 3" system (inc. 3" high flow cat")and tried to tune it for hours at my buddies work. They had a smog machine I could play with and both my buddy and I couldn't get it in spec. I had stock injectors at the time and was using my afc to tune. I've heard a full 2.5" system with high flow cat can get by. I dunno though.. I just eventually slapped my stock exhaust back on and passed with flying colors.

 

[DGajre777]

You might want to look into making a custom 2.5" exhaust system with a high flow cat and a stock looking muffler.