Buddy and I did the Ace 325 gear swap, 27% gear reduction over stock 2015 XP1K. Huge difference! If you rock crawl i highly recomend this setup. Clutch engauges very smooth and about 300-500 rpm lower than it did in exact same setup with oem 2015 gears.
I have also noticed in the exact same situation and trails a 40-70 degree belt tempurate drop. And i have not changed my driveing style at all.
Low top speed (according to speedo, that im guessing is off by a bit due to 32” roctanes) before 325 gears was 37mph. Low top speed with 325 gears is 27 now.
Havent had any room to see what high top speed is yet.
Bought the shaft and gear from partshark.com
3235450 48 tooth gear $92.03
3235451 shaft reverse 25 tooth $94.25