Top speed of my toad is 65 behind the MH, open road I set the cruise to 63, with an alarm on the GPS at 66 (hills). If not towing, which is almost never these days, I may push the speed to 65 to 67. If you are driving faster, you're doing it wrong. Enjoy the ride. As for the top speed of 80 (crazy fast), your engine probably has a speed governor, to limit engine speed.
On a side note, after I got my new to us MH, I was going through the computer displays, someone had the beast up to 83 mph!