I bought a set and got about 1 1/2 to 2 mpg better. But i haven't gone on a road trip with them yet. wal-mart parking lots are no problem now. I have a LOVE -HATE relation with them though. If you take your truck off road, ( mud- water) then you'll get to spend some quailty time repacking weel bearings. I'm going to try the overson eng hubs. I sure hope they are more watertight. As far as a HP increase, or more of a kick in the pants when taking off from a redlight? Dunno, I've got the fuel rate cranked way up. So it's hard to say.