It is indeed lighter, shorter, and louder than stock.
I originally replaced my stock resonator with an MRT H-pipe. I liked the sound overall, but it had a bit of rasp and harshness sometimes.
I recently swapped it all out for the FRPP by Borla GT350 catback and valance, which came with an...
http://www.borla.com/products/mustang_gt_resonator_part__60561.html
Straight swap for the Borla or FRPP by Borla X-pipe, and you will totally eliminate the rasp. I've had H, X, and this. H and X both were raspy at higher revs.
Under hood aesthetics for me, plain and simple. I started with the JLT, moved to the UPR, and ended up with Ford Performance and UPR hoses.
Pick the one you like the looks of and go with it. I've gotten about the same amount of oil in each of the ones I've used. A surprising amount actually...
I installed mine myself and it wasn't too bad. I do think though, that the pieces could be cut a bit longer. You have little room for error. I had to re-position my e-brake boot because it was too tight, and still it's a little tighter than I would like when its cold. But...I do love the...