I did a magnaflow resonator with a Borla muffler custom 2.5 cat back for my '12 SE.
thats a sound clip for you. between that, the newmisson mod and the snorkel delete i still average 37 mpg on freeway fully loaded with the wife, kid and enough stuff for a weeks vacation ( including all the crap needed for a 2 month old) running 87 octane. Haven't dyno'd it yet but the butt dyno says there is more pull in 3rd through 5th. 1st and 2nd seem peppier but not as nice a pull as 3rd and up.