I am a cummins man through and through, but I am currently looking at a 2003 GMC Durmax, I am wondering about bombing that truck. I am very knowledgeable about diesel engines, but EFI I am not. I am curious as to how it works if someone would do it for me or what not. I am also wondering about trannys in these trucks and turbo how much can they hold and such. I have a heavily bombed 1995 cummins.

The stock 5-speed Allison limits torque to about 700 ft lbs. As such, you don't want to exceed around 330-340 RWHP with a stock tranny. This equates to a power adder set on the 90-100 HP level. With a Suncoast Stage IV you can exceed 1000 ft lbs. The stock turbo with a good tune/hot box and a lift pump should put down 500 RWHP, which also be around 1000 ft lbs. To exceed that you need to look at a turbo or nitrous and a pair of lift pumps.

Afp1 pretty much nailed the bombing stuff. Now about the EFI stuff, if you can't do it or don't wanna learn how to do it, there are plenty out there that will sell you a hot tune or walk you through creating the tune yourself and some will even write one for you start to finish.


I really don't think you'll be dissappointed with the DMax its really competitive and getting more competitive nearly every day with more and more aftermarket parts hitting the scene.

Good luck, I doubt you'll be dissappointed if you go ahead with the purchase.



C-ya