I'm looking for more horsepower and gas mileage for my 01 silverado. So far I've already made a few mods but can't think of anything else to do without messing with the internals. so far I have: K&n intake kit, flexalite electric fan, edelbrock headers, amsoil synthetic oil, dual exhaust 40 series muffler, and a hypertech programmer. what else can I do in the price range of $0-500. I'm thinking about dropping some money on a MSD ignition kit, can anyone vouche for MSD?? Thank you all in advance.