Kev did it back in 06 & listed all the different types? I spoke about the difference between the 06 & 07 models when they changed from a twin spark motor to a single spark & how it effected the rev counter in the ASK KEV section.
Info in the mod section under.
RPM PICK UP WIRE IS THE ORANGE WIRE FROM THE ECU TO IGNITION COIL, OR RAP THE REV COUNTERS INDUCTIVE WIRE AROUND THE HT LEAD.
11/ After market Rev Counter Tacho
http://www.xt660.com/showthread.php?t=11616&highlight=counter