i put in my o/r x pipe when i had stock mufflers and it barely got louder, its pretty much all in the mufflers, its their job to quite down exhaust.. magnaflows are kinda quite but still sound good..

pricey tho

and ive heard many times about the whole, "you need at least a little back pressure" thing, but the more i think about it the more it doesn't really seem to matter once exhaust is outta the block, UNLESS the flow in uneven, like since we have dual exhaust if one side had a muff and the other side doesn't. it would make more sense for problems maybe