Until the Cruel, the GT1 featured the strongest cover from Motiv. The low differential block was the part that many didn't consider.
Being speed dominant, differential will be your friend.
Do up a 45x50@4". This will provide a medium transition. Playing out like you do, you are close to friction so a quick transitioning ball will tend to lose carry as the night goes on. You will need a hole, but throw it first to determine what placement to use.
If you are happy with the reaction as is, place a P2 hole. If you wish it to be earlier and smoother, place a P3 hole. If you want more push, place a P1.
You can also tune with surface. Box should be adequate given your outside line.
If you need further tweaks or advisement please let me know.