I ran a 17.5 actinium in my tc last night. I didn't break no track record but definitely fast. I was messing with my fdr during qualifying and once right before the race. Made it to the track late so end up missing two quals and was rushing a new setup. I have a good understanding of where the motor is comfortably fast and cool. No doubt next outing it'll lay down a better race pace.
Anyone tried running a 12.3 rotor? I didn't check yet but I'm assuming there's a 12.5 in there. The 12.3 in a 21.5 is a rocket, slightly less torque but has a tremendous amount if acceleration when geared at its sweet spot.