well i have to disagree a lil bit cuz once i put my wheels on my milage went down 1.2 mpg according to the computer in the truck. With the K&N, it went up a bit, maybe .5 or .6 mpg when i drive normal, and the hp increase was noticable. However, k&n brags about a 25 hp gain on my truck at 4200 rpm or something like that, i really dont know if your friends truck will have the same gains. Most of the kits say a 10-12 hp gain for those, according to my friend who has one (though i would research that, he is kinda weird).
Back to the topic at hand, ya that would be kewl if anyone could find out about supercharging it, im sure it can be done, but custom stuff always costs more than a prebuilt kit. THanks!
Nick