1. get rid of the stock flat cobra looking down pipe. about $90 if DIY
2. DIY 6637 intake, about $50 between fleetfilter.com and home depot
3. straight pipe exhaust. either cheap exhaust pipe or get a system $40 to $300
4. gauges, for you EGT and tranny temp are a must. boost is fun, but good to have to know where your boost stands. $300 give or take depending on brand. ISSPro and Autometer are good quality favorites around here.
5. IDM mod, about $100 through Beans Diesel (i think) i dont have any expirience with this one, will have to get others opinion on whether its worth it.
5. FPR mod. need a BB or small machine screw - increases fuel pressure. i did not do this.
6. custom tune chip, $250 - $500. DP, PHP, TW, Beans, etc. stay away from edge, superships and other canned tunes.
after that plan on more $$ for additional mods.
FWIW, check the turbo compressor wheel on that truck for damage. it will give you an idea on whether or not its ingested any foreign objects.