Right now I've got a Silverline axle back exhaust but I've been thinking about getting a catback or straight piping because my friend can do all the welding for me. If I did straight piping to the muffler and took off my cat and everything else would that screw with my ecu? I've asked around and everyone gives me a different answer.

 

You would need an o2 sim for the second o2 sensor after the cat i think. IMO straight pipe doesnt sound that good. You need to add a couple of resonators in there to help out the tone. Plus power gains aint that much. Id still get like a carsound cat or something off ebay.