inlet/outlet are like 2.25".
wait wait wait...i was thinking wrong.
the regular catback is 2.25", but the mufflers themselves are 2" inlet/outlet. after the Y pipe it is down to 2".
Maybe you can measure it?
I have an 04. Stock catback is the same. 2.25
I have an 04. Stock catback is the same. 2.25