just a few questions, recently got extractors and exhaust, and cant remember what my car use to rev out to, ppl have told me it was about 8500, but since i put exhaust and extractors it only seems to be 8100?

anyone know what they are suppose to rev out to?

and also, im wanting to take my resonator out so its a little louder, can this be done at home, or is it best to take to an exhaust shop??