Stock catback is good for 350 FWHP before having flowing issues...pretty sure the OP doesn't have 350 WHEEL horsepower. Only exhaust mods that actually increase performance are either headers/downpipe/u-bend delete or the PLOG...the converter in these cars nets you nothing when you delete it. Proven. If you want more power by doing exhaust mods...just get headers...and throw mufflers on it if you want a different tone. Keep the resonator...because if you get rid of it...it'll sound like ass.