If you're using a Sho-Shop Y pipe I suggest using some sort of muffler in place of the factory resonator. If you eliminate the resonator with an aftermrket Y pipe and aftermarket performance mufflers at the rear it will not make very pleasant sounds when the engine is cold, plus you'll have interior noise that will become bothersome on long trips.
I have 2 magnaflow 4" round mufflers at the rear of my svt, along with a removed resonator and optimized Y pipe. It is loud on the outside with alot of rasp when its cold, plus the interior sound on a long trip really starts to bother me.
I've heard something like a Magnaflow 4" round muffler in place of the resonator works well. I believe that someone on the site discovered a specific part number for the Eidlebrock RPM series mufflers to be nearly an exact match in dimensions to the stock resonator.
