Let's see...larger, faster-spinning turbocharger, all over-sized Aeroquip fuel lines, propane injection, nitrous injection (only time I've ever heard of nitrous on a diesel), and computer controls to tell the ECM (it's a 24 valve, so has an eelctronic injector pump) to change the wastegate usage (he's running over 40 psi boost ) and to add in extra fuel, along with a different set of injectors. The Cummins 6BT is a stout engine (possibly even stronger than the almighty 616/617); he's had these power settings for quite a while and yet hasn't blown a piston or the head gasket. I don't remember the exact numbers, but I think he's in the 700 horsepower range, and, I believe, is at over 2000 ft-lbs of torque. It's a dedicated racing rig; he actually has slicks in the back, and doesn't use it for towing or whatnot anymore...

He's also got a free-flowing intake and exhaust; I don't think his EGT's are that high (he drives sensibly for the most part)...he carefully monitors EGT's and turbo boost, and last I knew, hasn't had a problem yet, and he's been at these levels for at least 2 1/2 years...

If you head over to www.diesel-central.com or www.turbodieselregister.com, his handle's HVAC. He's local to me; I've actually ridden in his truck once...it's a very nice setup.