I'm not a big fan of Tekin motors. I like LRP X-12 motors, but they cog with some speed controls.

We have been running a Thunder Power 8.5 in my son's B44 and it is awesome. Geared properly 20/81 I think, maybe it's an 84 spur??? My son can run a FULL 5400 pack to cutoff and the motor temps 150*. Great powerband, and the motor has been in the car for 6 months untouched. The only thing to note is the motor smelled like it was overheated when it was new, I would temp the motor thinking it was going to be 180* and it would only be 130*. I was told the epoxy on the windings smells bad for a while. This has gone away now.