1) What year Car do you have and which engine
2) The Resonator alone will not help with performance much, now a CAT-Back will some.
3) Not sure about the sound because just the resonator alone with the stock muffler should sound about the same
Read my SIG I have a Vibrant Resonator and Magnaflo muffler and 2.25" custom exhaust it only slighly louder and the performance...I cant say for sure.
05 Matrix XR 4WD and 03 Vibe GT
"If you want Government to solve your problems, then you are the problem!" BMSR
Trix MODS: SRI w/ AEM filter, Vibrant/Magnaflow Cat-back, Alutec Lightweight Crank Pulley
GT MODS: Cosmo SRI, DRL, Auto Stop