exhaust!!

go flowmaster!!

i've got the 40 series single in dual out..
http://www.youtube.com/watch?v=DX5RcQbkVO0

 

Yea, all the extra weight on my truck in mods, such as 4" lift w/ sub frame, 35" tires, winch, Trans4mer, not to mention there is always at least 300 lbs. of tools, winch accessories & mig welder in my tool box and I'm getting about the same gas mileage I got the first 6-8 months I had it when it was pure stock except 33" tires. I think some of the mods for performance kinda balanced out the heavy ones, like CAI, dual exhaust, E-Fan, etc.

 

depending on budget I would go in this order. programmer ( I liked superchip for my hemi) intake, then exhaunst. after that go with electric fan then if you have the desire and money get manual locking hubs if 4x4. when you re-gear it with the lift and tires make sure you get a locker put in if you do a lot of off roading. it will be great to go more places with less worries.