Dave's right, there is only so far you are going to be able to go if the "sleeper" mode is what you are aiming for. Which is a pretty pointless concept anyway, because after the first race the other guy will know that you are not runnin' a stock machine.
The sleeper concept was from back in the day when people use to race for pinks and the sleeper was gonna spank the hopped up street-rod and win his wheels. But since not too many people race for pinks anymore its a mute point.
Just build your ride and don't worry about what it looks like. I thought I wanted to run the sleeper too, until I started going to Hp ratings that required stronger parts, lock-up, extended arm, NOSS head and realized there is no way to hide the stuff. Well unless you want to replace stock parts all the time, because if the person knows anything about bikes they are going to know what you have (except for internals) just by looking............. :beer: