Do it, you wont ever know unless you try it out. BTW PPE is rated HP at the flywheel not the rear wheels, so that 90 HP tune is like 65 to the wheels. And a bonus if you toast your Allison it'll give you a reason to build it!
Beat on mine for about a year on level 3 with no problems.Actually I had it stacked on an unknown tune when I first got it with the only problem being it kept throwing an overboost code when it would spike to 38psi. Reflashed the ecm and was mint till I got EFI. DOOOOOOOO IT!!!!
I've been running mine on 3 for about a year now and I haven't had any problems what so ever. Just don't get on it daily and you'll be fine. I keep good maintenance on my spin-on filterand fluid, that is key too. But I like to get on it to when I see Dodges and Fords, still no problems.