Can we talk motors for GT12/Supastox?

[plinth]

Hi, I've been racing GT12 for about a year now, and really enjoying it. I have the Core RC GT12 Combo (Pace 45R ESC + Speed Passion V3 13.5t motor) and it's suited me fine. Basically I'd like to know where I can go from here in terms of motor and esc.

I can't afford to upgrade to the ultra top-of-the-range hardware, so which motor would be a good step up? And if I upgrade the motor, do I need a new esc at the same time?

Cheers