I would agree polaris98ify, I had an older Indy trail 440 fan, flat out with a tail wind did 73, might have hit 74-75 with a long enough stretch to wind out to the bitter end. With the newer engines and technology also came power and speed, so 80-85 isnt unreasonable.
Also slightly depends on gearing, 2 up sled may be geared a little lower in anticpation of pulling a bit more weight.
98 Polaris XC600 (M10 suspension, Boyesen reeds, SLP clutch kit, SLP can)
95 Jag 440 (daughters sled)
"Speed is expensive, How fast do you want to go?"
"You must be fast, cause when I passed you I was Haulin @$$!"