i'm about to drive from va to colorado. has anyone had good luck with the chips that change your power and fuel mileage?  what would be the best chip to buy?  and what if any increase could i expect in my fuel mileage?  my 7.3l is a 4dr 4x4 pick up with 127k on it. i plan to drive to oklahoma pick up a truck camper (weighing in at 4k lbs) then driving to colorado and back to va. i normally get between 14-20 now.  14 overall when i drive to the mountains in va and closer to 20 when i drive the flats.   thanks