Omlet has this thread on the sprint booster:

http://www.jeepforum.com/forum/f67/s...eeded-1180912/

I have the Diablo inTune which allows you to boost throttle response. Going above 18% is too jumpy if I recall.... you can't start smoothly for daily driving. It definitely gives a more spirited drive. I got the inTune for $350 if I recall. If the sprint booster is going for $300 still, the inTune may make more sense.