On a street driven car, the sleeves should allow for more then enough horsepower safly. Look at this way, anything over 400hp on a daily driver is extremly annoying to drive on the street. Granted you can tone it back on a daily basis, but in order to reach that peak hp, you sacrifice more and more from the drivibilitity. So you need to ask your self, are you building a race car or a street car. If its a street car, understand that 400hp is still gonna feel amazing, and even on the best circumstance There arnt gonna be alot of chances for you open that power up leagally. So yea do you want the most power possible at the sacrifice of drivibility, or do you want a powerfull car that can be daily driven. Just think on that