I'm looking to put a few goodies on the old 4.3 vortec in my 2000 silverado 2wd. I already have planned a K&N FIPK cold air intake, a new cap and rotor (possibly MSD), and an MSD coil. I wanted to put underdrive pulleys on it, then i realized i would need a new or longer belt right? If so how on earth do you measure for one, and I've also heard that putting a certain combo of underdrive pulleys on will cancel each other out. If anyone knows how or what the deal is feel free to let me know. Also if anyone knows of any simple gains in horsepower i could get or any bolt on horsepower let me know. This is my daily driver so i don't wanna have it out of commision for too long or at all if possible. Thanks ya'll.