I have a 17.5 MMM setup with the high torque rotor and the green timing board. If you are hitting 160 after a full run to me at least that is about where I would draw the line.

By stock software, are you running blinky or a boosted class? In blinky, since you are only putting timing on the can I usually start by setting up my vehicle to top out towards the end of the longest straight, then adjust gearing for temps.

With boosted, I usually go with a big spur setup and boost at a given RPM range for the top end. Out here on the tight track it was common on say a RC10B4 to run a 87T spur with a 18T pinion when boosting a 17.5. When I was running blinky on the same vehicle, I think I was down to a 72T spur or so, and much bigger pinion.

Question for you, how many shims did you use on the rotor?