Ok, so I've searched on here for quite a while now and haven't been able to find the answer to my question. So the question is: what is/are the stock diameter/s on the exhaust of an '02 Cooper S? I want to do the one-ball mod myself but before I start cutting I need to know what size the exhaust pipe is and I don't have a caliper or any other way of measuring the size with any degree of accuracy. Thanks a lot for any responses.

 

I beleive it is 2.25" not 100% though

 

It is 2.25" to 2.5".

Ken

 

Just do the one-ball mod!!! I have it and love it The piping size from the cat to the resonator is bigger than the piping from the resonator to the muffler. not sure of the size. think it is 2.25"

 

Cat to Resonator = 2.25"
Resonator to Muffler = 2.5"

 

Alright everybody, thanks a lot. You've confirmed everything and I'll be doing the mod any day now. Thanks again

 

Only cost me $40 and 20 minutes in Vegas. Can't imagine doing it myself for anything approaching that cheap

 

Same for here in Chicago's burbs.

 

in NJ it cost me about $70.... i'm upgrading to an Invidia system soon. Might try to sell the one ball.

 

Is the one-ball mod just for sound or is it also helping with reduced back pressure?

 

Both

 

Hi,

Hey, I live close to you in Minneapolis. Just wondering, did you have the one-ball mod done yet? If so, where did you have the work done and what was the time/cost? Are you happy with work? Notice a difference? I'm considering this mod myself. Thanks!

Benson

 

Can't say that I noticed any performance or gas mileage differences, but when I lift the throttle it sounds great!

 

Any California Smog cert issues?

 

i dont believe smog cares about mufflers, as long as you have a cat