I just got my truck back. I had purchased the JBA shorty headers a few months ago. I got the shortys cause thats whats supposed to help in the low rev range versus long tubes which help air flow at high revs. After putting on my 37"s my truck started getting about 9mpg in the city and around 11 highway. Tonight on the way home (mostly highway with a few stop lights) I got 15.5mpg according to the truck! Instead of the truck down shifting up little hills and trying to find the right gear at certain speeds it now just cruises like it's supposed to!