I don't know what the new 210's turn or run, but they are slower than the other boats. The older 210's probably did around 40-42mph depending on surface conditions, bimini up/down, wind, elevation, and load. If you were loaded up, bimini up, higher elevation, etc., it could be on the money. At higher elevations, your RPM and speed will suffer.
@jawsf16 had a 210 I think, but it was an older one. My recommendation is to wait a bit and see if anyone with a newer 210 replies. It isn't far off the mark if any of the above conditions were high. Now that I see your in Billings, your high altitude...that will do it. If it is too slow, you may want to look into solas impellers designed for higher elevations. It is all a trade off. You don't have the horsepower to overcome, and all engines/boats/airplanes/cars/trucks suffer at higher elevations compared to sea level performance. And you will never see what sea level operators report, no matter what impellers you have. So make a decision on what you want. Either out of the hole power, or speed, because a change in pitch on your impellers can only move in one direction from what you have now. A less pitch impeller will give you less hole shot, but it will spin freely with less resistance, and that will allow the boat to speed up a tad. An impeller with more pitch, takes a better bite, and will get out of the hole quicker, but the additional drag from the steeper pitch will slow your top speed down even more. If you can live with it, the 210 is a great boat...but it will suffer more and faster as the elevation climbs. But at just over 3100', you are not all that high, but it is enough on an already underpowered boat. Don't get me wrong, when I say underpowered, it just isn't a high output 320HP 230...or the 360HP 240. Even the single engine 190 would suffer up there, but they offer the gas guzzling 192 that is supercharged that would do well at elevations above you. I know this sounds like the bearer of bad news, I am sorry. If you just can't live with it, consider a high output model or the solas impellers designed for higher elevations. But I do want to reinterate, if your running at 3100', then that is not all that high. And you won't suffer all that much, but you will be less than sea level 210s. Jaws! A little help here!