I have heard the JDM type r had a 2.5" header & catback exhaust compared to the USDM 2.25" type r exhaust.

Does the muffler on the JDM type r have a 2.5" inlet to it then?
or does it get smaller to the size of the USDM type r muffler?

I'm asking this because I have a JRSC GSR and I need a quiet 2.5" exhaust setup, and I was thinking that doing a header w/ 2.5" collector, 2.5" carsound cat or random tech, and custom 2.5" piping with a (hopefully) 2.5" JDM type r muffler. This would keep it relatively quiet while providing good flow for my SC car, since most aftermarket catbacks are either 2.25" for NA cars, or 3" for turbo cars.

thanks,
Martin