I'm pretty sure that button
DOES NOT actually reduce
power as such, even if Martin does explain it that way, but it
does enhance the Nanny's attention to your Spyder's stability & braking, traction control, ABS, EBD, Yaw Sensor etc, and she won't let you go quite so crazy without stepping in a bit earlier than she might if you were riding solo.. :lecturef_smilie: And
any weight or tension equivalent to more than about 20 pounds on the rear seat
will trigger that switch & put the Nanny into hyper-vigilance mode cos she thinks you've got a pillion passenger aboard!
So Martin's little cap is just one way of making sure that you don't needlessly retard your enjoyment when you simply strap a parcel onto the pillion seat, or maybe tie your jacket down onto it tight enough that it won't flap in the wind or blow off as you whip thru the twisties!!

But you
really should remember to remove that cap &/or any other 'switch trigger avoiding' device you might have fitted when you do carry a pillion, or you might find out how easy it really is to upset &/or flip one of these things when your pillion passenger does exactly the wrong thing at exactly the wrong moment and the Nanny doesn't step in quick enough or hard enough to save you & your pillion from your own exuberance - or your own stupidity, but maybe that was just me?! :dontknow:
Just Sayin' :thumbup:
Ps: that 'pillion detecting under-seat switch' doesn't have
anything directly to do with the rear suspension &/or its height settings either; any change to that is simply a feature of adding extra weight to the pillion seat that lowers the rear suspension a little, thereby changing the height detected by the sensor attached to the swing arm, which triggers the addition of more air to the air bag -
IF the ACS is working properly anyway!!