Clutch pedal travel.

A bigger bore master cylinder will give you a shorter travel. Otherwise, you could try modifying the linkage to give a different ratio. I've driven a friend's 944 once and found the whole experience to be less than sporting. A shorter clutch would probably help, but I found the gearshift to be pretty long and loose as well.

Oh, but while I think about it, you might need to have your seat in a position to reach the floor with the pedals, in case you need to push the brakes all the way down. In normal driving you won't ever push the brake pedal down to the floor, but you never know when some kind of emergency situation may require you to do so. Brake fade or losing fluid from one circuit of the brakes would be the most likely scenarios.