@divouneh The pintX should be able to do 20. It's using the same voltage as the XR, which I've inched up to 23, 24 mph. However, I'm about 140-150lbs (depending on what the semester is looking like)
You should check your tire PSI and see if it's gotten a little low. Also, don't attempt going fast on windy days. Outside of your board, the biggest two things that affect speed is weight and wind resistance. (I think)