Im buying a ITR oem cat back, will it bolt right on to my 95 gsr or will i need a new cat/header or are they the same?

 

It won't fit w/o modification to the B pipe, which any muffler shop can do. The GSR is a slightly smaller diameter pipe. You can chop the front off your GSR B pipe and have it welded to the ITR B pipe.

 

The part that connects to the GSR cat you mean? Would I be able to just get a ITR cat?

 

You can try, but I don't know if the length will be correct or not. Also an ITR cat will need the second 02 sensor hole plugged since you're OBD1. You can also get an aftermarket cat and have flanges welded to that. A lot of trouble for a stock exhaust, in my opinion.