GP shifting is the reverse of regular shifting. Regular shifting from Neutral is 1 down (1st gear) 5 up (2nd - 6th gear). GP shifting from Neutral is 1 up (1st gear) 5 down (2nd - 6th gear). If you can unscrew a bolt you can do it to your bike. The rod (in front of your oil filter) from your shift lever just needs to be flipped. You just undo the bolt. and flip the rod to the opposite side and retighten. You don't have to remove any plastics and it takes about 1 minute to do.
i believe the reason for the gp shift to to help during high-speed left hand turns. with the gp shift, you can still upshift as you are exiting the turn while still in the lean, without having to wedge your foot under the shifter. this way you just step on the shifter and go...