Motor selection

okay, so i decide i'm gonna go with 16 cells. This truck is gonna be tossed around like a rag doll. sooo...

feigao 8xl
9918
16 1.18 cells
all stock except rpm arms, steel cvds, ga 7075 bulks, ue 6 spy diffs, ultramaxx tranny in aluminum case (yep go my self a GPM alum case lea want, leo get), and proline powerstroke.

now that you know the basic weight and powertrain of this truck, what gearing should i run? I still have that Dave strobeen slipper, but now that i'm gonna run even more cells, can i go to 20t pinion?