06 X15 That is also what worked for me for surfing.
Set to Manual, Press and hold ON at about ~2600 RPM's and hit +/- to adjust from there.
I tried RPM mode and it would not engage, it was locked to 2400 but wouldn't pick up. Maybe I was coming out of the hole too fast, expecting it to kick in and before I realize it we are already going 15-18 MPH and the surfer is haulin a*#
