Truck Modifications

Heya All,

I'm still a few years away before buy my 5th wheel, buy was hoping to look into truck modifications while I'm waiting. I know it will be a diesel, but keeping my options open as to which one (right now I'm favoring the Duramax in the Chevy 2500HD or 3500)

Anyways, i was wondering if you might suggest some modifications i might want to make and/or avoid. Some of the things I've been looking at are:

exhaust brakes, after-market brake controller for trailer (i.e smartbrake), performance chips, sway-bar or other suspension improvements, after-market air flitters, air jams / airfoil (or what every you call that thing on top of the cab to make the rig more airo dynamic), and/or anything else i might want to research over the next year or two.

thanks for you time,