These may seem to be stupid questions, I did a search but nothing much turned out. I have several questions about the CATBACK STi exhaust:

1. I would like to know the difference between a JDM STi stock Catback exhaust and an USDM STi stock Catback exhaust. Inch different maybe? 3" vs 2.5". If so, can I replace it even the dimension is the same?

2. I heard the one from here is not stainless but the one from Japan is. True?

3. Where can I get the JDM one and how much would that cost?

Thanks a lot in advance for inputs.

CWboss