ive finally decided and im about to purchase the RS-R DP and greddy EVO2 exhaust. before i do this i wanted to check with you guys. i noticed that the piping is 80mm on both of those peices and 3" is 76mm. do u think that extra 4mm could make any sort of negative impact on the performance of a regular 3" exhaust, or does it not really matter and i should just go ahead and order the part already. let me know what u guys think . thanks

 

80/25.4 = 3.15". That isnt much more than 3". You'll be fine.

 

It doesn't matter, the wider the piping the better ...

 

Actually, it does make a difference. There is deffinetley TOO large. Don't forget about the scavaging (sp?) effect... With a turbo setup, larger is sometimes bettr but too big you get negative effects. It all depends on who you talk to driving style and your setup. I know Works claims that through thier R&D that they made LESS power with the 3 inch on a stock turbo. By the question I am guessing you have a stock turbo. 3 inch is as big as I would want to go. however, with a larger turbo you may want bigger. AMS uses a 4 inch exaust on thier setup for example

That being said, if you found a setup you really want and you don't care about the small details of how your car makes power, like every little tenth of a second. Then I would say that that small difference you will not notice from a 3 inch

 

I was hoping noone would start this BS. It doesn't matter on a turbocharged car, the less backpressure, the better. Bigger after the turbo is better as it improves the VE, period. There are countless threads on this ...

 

There is no scaveging effect AFTER the turbo. When will people learn. FYI - The EVO 2 exhaust necks down to 2 1/2" where it bolts to the factory cat/ cat delete pipe.

 

ok so if the rsr is 80mm and the evo 2 is 80mm but necks down to 2 1/2 where it connects to the RSR, does that make a difference in terms of performance? or is that just what it is

 

I will make a little (read very little) difference as there is a bottleneck in the part that is 2.5 inches. You want it to be 80mm all the way through if possible ...

 

i guess im just doing RSR DP w/ greddy evo2 catback . lets hope i dont regret it .