Tried to get an answer in Allison OEM but no response. I put 120hp program in, locked out O/D, 2 wd boosted launch, and no audible wheelspin. No limp, loaded 65hp and truck continues to run fine.Will the ECM pull fuel based on T/C slip w/o limping? Will the TCM do something similar? There was a shudder, was that the T/C slipping? I'm curious what was happening in there and if anyone else has experieced this. I don't need the trans mods sermon; I know it will be necessary; now is just not the time.

Can you smoke the tires on a 120hp 4x2 boosted launch?

I could with the 65 pretty easy. The ecm does have a rpm limit for when the brake is applied, you may have noticed it won't try to rev all the way when you try to powerbrake it. If you have really sticky tires and good brakes you may have to let the brake out a bit to make it spin. Hold them tight and get it revved up, then let off the brake a little and then push it again. That way it will let the back tires start to spin and then you grab the brake again and it will keep the rear spinning but the fronts will hold.