Documented horsepower gains can't be beat 6.4 gas
After putting on this kit I noticed a very different sound in the cab of the truck (louder) under load/acceleration, just from the air draw. About 2k+ the sound was pretty cool but there seemed to be a bit of a drone or something in the cab (3k rpm). As I mentioned the sound was very cool imho, but not so much the drone. The drone as I mentioned did go away after installing a Magnaflow muffler (part # 12909) Not the cat back system just the muffler. Well worth the money.