Are you planning on going the turbo route? Even though your exhaust is giving you hell right now, you should be able to salvage it. Take it to a good muffler/exhaust place. If your going to turbo your car, a test pipe will yield good results. If you don't want to break the law, a good shop could hook you up with a good high flow cat and modify your exhaust so it fits like condom. Just make sure they don't wel everything together so in the future you want to change something you can simply unbolt it.