Well the motor is built strong enough handle about 450hp, thought at that point your definently asking alot of the stock sleeves. I wasnt gonna run more then 26psi because on a compressor map that was right at the top of the efficiency for the turbo and motor, any higher and the turbo is working to hard and starts becoming more of a heat pump. I havent seen the dyno sheet so i dont know if it made power all the way to redline at 28psi, but id imagine its close enough to max efficincy to have been alright.