As I work on the Spectre, it is obvious that Kawasaki was paying attention to which products were selling and what the market place was looking for. I had totally forgot that they had a shafty in the 750 class and I've had a few other shaft driven bikes but they were larger, in the litre and over size. Most were darned heavy for the size and the Spectre is relatively light, given the build of the frame and drive train. From what I have been able to glean from some of my reading, the Spectre used the basic engine from the 750 GPZ but I have also noticed it does not have an oil cooler so I'm not so sure about how close the motor is to the GPZ spec. I do remember my 750 GPZ was pretty fast but seemed to lack a bit in the low RPM torque area. I guess only some seat time will tell about that. I bought a 2005 Yamaha V-Max in October that was about in the best condition anyone could ask for and she was a great bike for a larger rider. I'm 73 years on the planet, 58 on motorcycles, 5'6" and 145 lbs. That 680 pound beast was just to much to haul around, I sold it within a month and lost my left cheek of my rear end in the process. They were an impressive machine but I still think my 900R and FZ1 would spank a V-max without breaking a sweat. One word about a good wife. Read the Four Agreements and never say anything to her that you will regret if/when she's gone. Almost every day I will think of something I said in disagreement and deeply regret it. You simply can't take back that which you should have never said in the first place. Ride on, and be happy.