i have no resonator and it does not sound that loud.. when the engine is cold, the exhaust sounds a bit raspy, but once it warms up it sounds smooth and clean. i am not a fan of big loud exhausts (unless you have a muscle car of course, but thats another topic) and this exhaust is just right for the price.
if you cant make up yoru mind about the resonator, i suggest just leaving it on and if you want it louder, cut it off later...
edit: just reread some of the latter posts, the cat definitely adds some noise reduction. ive been catless with this dynomax and it is pretty raspy all thoughout the rpm range. too ricey for me. if i had cams and some other internals it might be worth it to go catless, but for now this is fine.. no resonator ftw!!!