mufflers are good but you dont get the same tone and the low rumble as a no muffler exhaust would sound the bonus of mufflers would be a little boost in economy and it would make your truck a little faster no matter what you get until the pipes "break in" your fuel economy will go down from the change in backpressure still saying if you want them to be loud and a true rumble go with no muffler if you want fuel economy and performance go with a muffler