From Wikipedia, on the entry for my new bike:
The pink wire connected to the ECU of some of the later 900 bikes retards the ignition timing in the lower 3 gears to make the bike more user friendly, limiting the ability to spin up the rear wheel out of corners, and reduced wheelie tendencies. Disconnecting this pink wire removes this feature.
I’m pondering installing a switch on this wire, and labelling it “DEATH” and “NO DEATH”. Although for the latter position, I may go with “LESS DEATH”.