the only real answer to this question, is all the abuse right up until it explodes, the input shaft is weak, the od band is very weak, they snap when the vauge shifting goes in and out of od, and then comtaminate the rest of the tranny and it all breaks, but with anything with enough money it all can be fixed, the cheapest option is to put a 5sp in, i have 1300 in my aod, and need to spend at least that much more, and for 1000 i could have a t-5 conversion, i was dumb , this all being said i am a fan of the auto in general, but specefically the aod is crap, but if you get a good shift kit an good input shaft and good fresh internals it will be ok, to answer your question, i have a h/c/i and roughly 300 to the wheels,i worry how long it will last, any more than that without serious upgrades is certian death