I have ordered an SP63 and I feel that it will give bottom end very similiar the the stock twins in TTC mode. And on the roadcourse the extra hp and reliability is a plus. I think concerns with lap on a roadcourse are to some degree not needed. If your below 4,500 rpm on a roadcourse than you need to learn to drive and not focus on your hp. At this rpm and above almost all turbos will give you meaningfull boost. They should also have spoolup charicteristics that will be good enough to overwhelm the rear tires. 
Go with a medium sized single and I'm sure you will be more than happy. I will of course give everyone my impressions as soon as I get my SP63 installed and I go to the roadcourse.
Later, Steve
Go with a medium sized single and I'm sure you will be more than happy. I will of course give everyone my impressions as soon as I get my SP63 installed and I go to the roadcourse.
Later, Steve