Id say its probably 3 cuz the cats are pretty big, but you should just go to your dealer and ask them they probably have the answer

I'm really really confused.

ESC tunning guess at 2.25", two folks at autozine guess at 2.5", and one here guess at 3.0"???

.............speechless........................... ..........................

Im just going by the size on my 1.8 its really big I think 2.5 or 3' but i think your best bet is to just call the dealer, its not like there going to charge you for asking a question

I tried, but they're unable to give me an exact answer, and I lived far away from them, I will try to call couple more dealers here in CA to see if they have an answer for me or not.

Anybody know any good CS and knowledge dealer here in CA, if so, please provide me with their phone number, and also the name of the rep would be best.