Scooby,
I would recommend using a Kennedy ECM tune. I have several tunes (Predator Diablo
sport & Edge Evolution) that I do not like because of high EGT issues under load. The Kennedy tune gives a nice boost in HP and fuel mileage (25 MPG highway under 65 MPH) with relatively low EGTs. Additionally, I would stay with the 285/75/16 tires or smaller. I know someone that put a lift kit and 35" tires on his Duramax and now when he hits a hill (even a small hill) pulling his 40' toy hauler the truck goes into limp mode because the gear ratio is way off and it forces slipping in the transmission. My truck is a dually and the factory tires were 215/85/16. I converted it to 225/70/19.5 and had Kennedy do a 5% speedometer adjustment to the ECM when he installed his tune. The 19.5 tires have worked out very well on my truck but I would not recommend going to any larger tires on a dually. Good luck with your truck mods.
John
Last edited by CoyleJR; 03-24-2017 at 13:11.
*2006 Chevy, 3500, 4X4, DRW, (LBZ) D/A, CC, LT, 252K Miles, 19.5" Wheels, Mag Hytec Transmission Pan and Differential Cover, SS Grill Guard, Racor 2 micron aux fuel filter, 100 Gallon Aux Fuel Tank, using Edge Evolution, Predator Diablosport, Kennedy ECM tune, Fitch Fuel Catalyst.
*2006 Four Winds, Dutchman, 36', RV, D/A, 5500 Kodiak.
*1993 Harley Davidson, Turbo charged, Springer Softail.
*2007 Pontiac Solstice.
*2005 Jeep, Liberty, CRD (diesel).
*Full-timing in USA, see America first.
BUY AMERICAN or CANADIAN, NOTHING from CHINA .