that has to be spead up
No way is that spead up, if you see grass drags in person they are very very fast, some even faster than the above.
Try a 15" by 136" track with about 100 1" studs ripping into the earth for gras drags. There are quite a few modded sleds under 450# making over 300HP out there. All the new big bore sleds are around 440-550#'s now and are all making 150-175HP bone stock.
On top of that these are race sleds with custom tracks that are quite a bit longer than 136" tracks. There are some race sleds out out there that are pushing close to 500hp.