depending on my mood i have run upto 100bhp, but normally run around 70, thats more than enough, if you do it tho make sure that u get a pressure guage, heater, purge system and a progressive controller, if you dont use a controler it shoves all the power all at once, and can bugger the clutch quick, also recomend uprating the clutch too to help prevent it, it really gives a good kick up the a$$ when the shot hits tho, scared the crap out of me the first time i dared use it tho lol! id download the guides off turbobits first to have a read through, no down sides as of yet, just got to change oil regular really and watch the clutch as said before, il pm you some pics of my install tomorrow if you like, iv done quite a few for people and all with no problems, as long as you dont go crazy its safe to use imo