for 17.5 blinky i have 96-100 in car. 47-55 pinions seem to fit. 64p obviously. 47? weird eh. thats a ratio 4.22 but im trying it with a high rpm rotor to see how it stacks with the higher torque motors like the d3.5.
Have the stock rotor too, but from testing at our last indoor night, the power band was easier to handle. less likely to rip the ass end aruond exiting corners and had more top end rip on the straight.
3.6-4.0 seems the norm for this class. 3.8 seemed pretty lazy though. fast..but i tend to slow down for corners to save my tires. drive a shorter line if possible.