They are probably fastish due to the lack of long travel suspension causing extra drag and banging off a 8 inch bump felt wicked when a new sled would just skip right over it. Plus you could pick up the front or back end of the sled with ease. Still fun to blip around on for a little bit.But the vintage sleds sure seemed fast when they were brand new! I have very fond memories of my first two sleds that were single cylinders. To this day I have been wishing the big bore single would return in modern form.
The Blast makes 65 HP. Probably my first 10 or so sleds didn't make that much HP until a got a Polaris 500 Centurian. After the Centurian I had a few Polaris 340 Indy's that made 56 HP and they seemed wicked fast.
I did have a '72 full factory mod/race 650 Polaris triple, maybe that made a bit more.