I went in today for an quote on putting 2.5" pipe from cat back and adding flowmaster mufflers.

I assumed it was 2.25 from the factory but guy said I have 2.5 at cat and 2.25 coming out the resonator...?????

"09 RT"

automatic : 2.25"
manual : 2.5"

automatic : 2.25"
manual : 2.5"

Just came in from looking myself. It does seem that there is 2.5 from the cat to to res. and 2.25 to out of res to tail???

And I have a auto.

its actually a metric size. 2.25 pipes will work cause they will just use weld around the fitting