I have been running my Jammin x1 with the 7.5 and love it. Granted it doesnt have the top speed as a 6.5 or the others but the off line torque is insane. I would look into making sure that you have the gearing right for your application. you can go to www.teamnovak.com
and they give you a starting point, but you can also call them and they are very helpful in getting your stuff dialed. Hope this helped.