[jakeru]

Those aftermarket shifters have some threaded stop adjustments that sound like they're essential to get adjusted properly, in order to get rid rid of fore/aft slop. I'd check those and make sure they're adjusted properly - should be tight but without causing noticeable friction or binding. Might benefit from some thread locker to keep them from moving if you did find them loosening. Might be able to access by lifting up the shift boot.

While you're at it, inspect the socket fitting underneath the shift console to make sure it's not binding or hanging up on something. If not in good shape, replace with new - (they're available from Porsche as a separate part). I've seen some with shredded rubber areas before, and that can't be good. If you have short shift, it's also probably best to verify that the original green plastic "shield" that is originally under the linkage is removed (for adequate additional clearance which I think is necessary with the aftermarket short shifter - maybe it was installed incorrectly).

Next, check and consider adjusting the shift rod adjustment that controls the front-back cable position, also below (and just in front of) the shift console. You may need to remove or loosen the plastic center console to get to it. Adjust it to adjust the knob position such that the r,1,3,5 are easier to reach with knob in a neutral range of motion.

Next, after doing all that if still not happy with the results, check out the rubber bushing back where the shift rod terminates, and connects to the transmission input lever. Make sure the rubber bushing isn't torn, or it could cause excessive play.