[starscream]

3mm isn't much
An easy solution to this is to run slightly bigger gears.
What vehicle are you using. What is the current pinion spur? 46/15?
it sounds like 48/16 would fix you up.

You can always run your 17T pinion and set your throttle end point down to 85 or 90% until you get new gears or make a small spacer.