all the GT's that i know of personally are P.I. headed GT's and they run in between 100-150 shots with tuning, the guy i bought my last nitrous kit from was running 125 shot untuned......
really none, i've had motors i've sprayed for years, a friend of mine is still riding on a motor i sold him that i had in my notchback for about a year of constant nitrous abuse, i sold him the motor in 2000, he's still riding and spraying it with no problems, as long as you dont over rev while on spray, spray at a low rpm, or spray with low bottle pressure, you should be good
Im new to the site, but from what ive read, i would listen to sprayed pony, hes seems to know quite a bit. I just finished my junior year in my automotive engineering program, and just got done with a dyno tunning class where we talked about all this kind of stuff. As long as you tune properly, your not gonna see any more effects than you would running any other kind of forced induction.
I'd say probably no more than 100 maybe 125 with the stock plastic intake. After that is upgraded i would say 150 at max. As long as it's tuned right you should never really have a problem of any sort.