Although I have a much newer machine than sscotsman

, my performance is quite similar.
1976 MTD/Dayton 826 two stage with original 8 hp Tecumseh.
It appears to have a 16" auger, 14" impeller, and 6" discharge chute.
The following applies with 4 to 6 inches plus of snow. Lesser amounts don't seem to give the machine enough snow to produce any velocity. Probably half those numbers with 2" of snow.
Cold powdery snow (air temp of 20 or below) Throws 20 to 30 feet plus.
Under the right snow conditions, I can put the snow on the sidewalk of my neighbor across the street.
Average snow (20 to 30 degrees air temp) - 15 to 20 feet.
Wet heavy snow/slush (air temp of 30 to 35) - 2 to 10 feet.
I have never had a plugged chute in over 30 years of use.
Several things I have learned:
Run the motor at full throttle once it is warmed up to operating temperature.
Regulate your speed by what gear you are in.
Don't go too slow. My old machine has 5 forward, 2 reverse speeds and I usually run in second, but quite often in third.
It seems that the machine works better when the auger and impeller are pretty well loaded. I go as fast as I can without the motor laboring. If it sounds overworked, I drop down a gear.
Fourth and fifth are just used to move the machine from one location to another.
EOD and really deep drifts (3'+) sometimes require first gear and I still sometimes need to disengage the drive wheels and let the machine do its job.