If your heart is set on headers the best route for tha a mount you have to spend would be S&S headers ,hi-flow cat and a custom built cat back to Magnaflow muffs ,this is about the nicest sounding system I've heard on a GP ,of course there are other mods probably better at your point but exaust mods will allow you to take better advantage of future mods,as far as the stock cat back it's ok but I would go to at least a 2 1/2" custom with a better rear Y design ,a good exaust shop should be able to hook you up for about $500.Chico.