I need an idea of how hard it would be to cut off the stock mid pipe / catback and replace it with an aftermarket system. Is there any type of how to out there with some decent pictures / write up?

I'm thinking to get me started with the modding bug (had it bad with the v6) I would pick up the mac prochamber mid pipe for my GT, and save a little time before buying a full cat back system. Is it possible to have a 2.5" midpipe and 2.25" cat back? I know this sounds stupid but I"m a 17 year old without a job at the moment so money is tight.

Thanks, I appreciated it.