Got my E-trex Vista out (GPS) and did a test for speed.
Low Range
Forward 3.2 MPH
Reverse 2.0 MPH
Mid Range
Forward 6.6
Reverse 4.0
High Range
Forward 12.4 MPH
All of the above are at maximum RPM's. Looks like I could maybe adjust mine up some. I was always OK with mine forward but I did notice some slowness backing up the driveway when plowing. And my GPS is a pretty good one and should be pretty darn close to being right accurate. I did do some test with it a year or so ago and it was right on.
murph