I have an 04 gt with a bassani mid pipe catted but a stock catback. My question is that since my midpipe is 2.5" and my stock catback is 2.25" with different in sizing of pipes will that cause any problems with my car? I don't plan on upgrading my catback for awhile but will. in the mean time I shouldn't have any problems?

 

The different size in pipe diameter will not make a difference between sound or performance. You will be fine.