Just about the constant hi RPM thing..
Keep in mind many of the automotive marine conversions, are run continuously for hours and hours on end, uphill, with a red line of about 4k,, and std cruising rpm of between 2400 and 3500 rpm,, hour after hour, for hundreds of hours.. uphill..
Some boats run wide open (governed) from dock to dock,, all their lives..
jmo
The discomfort is solely yours,, not the engines..
