I am going to start racing short course, either mod or stock. I h a few questions regarding brushless motors.

First off, I found a Novak Havok 8.5 motor..how is this different then the SS motor?

Secondly, what is the main difference between the Ballistic Racing 8.5 540 size motor and the Novak SS pro 8.5?

What would be better for short course?