In 6.5T guise the Novak Ballistic produces 390W (6400kV) of power compared with 340W (5800kV) for the 7.5T version.
The LRP 6.5T produces 406W (5300kV)
So in essence I would say the LRP is slightly more powerfull and the 6.5T will overall be more powerfull. Whether that makes the car more drivable or not though will depend on other factors such as ESC setup, gearing and track conditions.
I would recommend the Orion motors though as a very good (smooth) package (although I do intend to try something different this winter!).
Spec links for the motors below.
http://www.teamnovak.com/products/br...spec_chart.htm
http://www.lrp.cc/en/products/electr...-wind/details/