Dont go out and spend more money on a exhaust system(new catback) thats going to give you almost the same hp numbers as your custom one is, not worth it in my book. Just have the exhaust shop install a resonator in it and it will calm the noise and take the raspieness out of it. Resonator and install should run you any where from 50-70 bucks...at least thats what I had to pay. They usually have three different sizes usually depending on how loud your exhaust is and how quiet you want it to be, longer the resonator the quieter it will be.