I'm Kind of new to this on road thing, but I have had my GTP2e for about a month. I am running the mmm 2250kv combo with a 20t pinion. With the spool in place, the rear end is all over the place upon take off. I have to really really ease onto the throttle or the thing will slide all over the place and eventually spin out. Now with the center diff in place i can be very aggressive with the throttle. No spin outs and much much more fun to drive. For me, the center diff is a must. Hope this helps.