i stuck a mamba max pro ESC and a castle 1410 3800kv 4 pole motor in my XS SS.
its recommended (or it was to me when i put mine together) that you use a 4 pole motor as the truck is fairly heavy for it's size.
and i will flat out tell you right now, with the motor/ESC combo i put in mine, a 25c battery will not cut it, im running one and iv got the most inconsistent "turbo lag" iv ever seen in my life and it gets maybe hotter than it should. id go at least 40c on the battery and in the 5000mah range (at least for my set up)