Regarding PedalMax or SprintBooster, I was set on spending the $300 to try it out, but I came across this cheap substitute to improve the throttle sensitivity. The guy who came up with the mod equated the throttle lag with our acceleration pedal having some dead space. It's like when you flick a light switch, there's a fractional distance the switch travels before the light turns on/off. I did this ghetto mod myself yesterday and tried out different thicknesses of the tape (you'll know when you've put too much!), and my throttle response does feel a bit more responsive (the improvement is enough for me to spend the $300 I set aside for the SprintBooster on something else). Best of all, if you don't like the mod, you can always just remove the tape (no harm done).
Anyway, check out posts #3, 11, and 41. Any experience with this? - Forums at Modded Mustangs