Don't kid yourselve's into thinking that by removing your chip before service that the dealers aren't on to the ways of "Performance Enhacements". Ford is cracking down big time on enhacements. And if they see you have propane injection, BIG RED FLAG. The dealer can and will void warranty on trucks with enhancements. Motohead, what year truck is yours, did I miss that??? There are sooooo many mods you can do to the trucks it is amazing. The Diablo chips run higher EGT's, so I would make sure you install a downpipe and larger exhaust. Like others said here, go to TheDieselStop.Com. There is a wealth of info there. I have 2 PSD's, an Excursion, ATS 3 stage chip + 4 inch exhaust, and an F-350 SuperDuty with 150hp chip, propane,and other mods. As far as mileage, I really don't keep track of it, the trucks are tooooooo much fun to drive slow!!!!!! As was said earlier, go to the above forum as there is a wealth of information there. Good luck.