We have started to test the new R1Wurks Spec Motors recently, and we really like what we have discovered so far.
On track with a Sedan, the R1 13.5 gave us a hot lap 0.2 tenths faster than the d3.5. Two whole tenths!!!!
What we can tell you is the motor build and quality is as good if not better than what is available currently out there. The motors have more RPM than the Gold Standard D3.5, so much that when unloaded you can hear it rev up in the car a lot. The R1Wurks motor sounds more like a mod motor than a 13.5.
In a 13.5 sedan we are gearing 2 teeth lower than with a D3.5, right around 4.5 overall. We are running the timing around 30 degrees on the end bell. Our track at RSD Speedway is 96x40ft, and the motor still has more top speed (it is visibly faster) and has a lot more mid range power than our benchmark D3.5. Much like it sounds, it runs more like a mod motor than a spec, always having power available when the peak is high on the battery. We actually dialed a little negative expo on the throttle to mellow out the throttle input an make it easier to drive because it just has so much rip.
In our 12th scale, we have not quite figured out the roll out yet, but the lap times are already within 1 tenth of what we do with the D3.5. The rotor might have too much strength. Maybe we need to gear up, but we still have to play around with it a bit more to get it dialed in.