Yeah! i realise this. Had it on a chasis dyno & the 650 was only down 13 HP on an 850 D/P.
Actually, its the 850 i use to produce those 1/4 mile times, but that 650 is a real side-winder as well. Pulls best to about 6100-6200, but just holding, it still goes pretty hard out to 6800.