Something I need to try on mine. Was thinking of putting it on level 1 to tame the wheelies a little bit. Currently on level 3 and she wheelies like a good'en!
Fitted my new gds pinion/spur (21/50) yesterday and only gave it a quick test in the back garden to make sure everything was good, which it is thankfully. The new gds hardened gears make a good noise too, just from the sound you can tell they are harder.
My truck should be running a little quicker than 18/46 looking at the ratio chart. 55mph I reckon, should be tasty.