I figured I'd try some different pads. On one of the Mustang forums another S197 owner that does track days upgraded to aftermarket calipers and rotors on his car. He had some spare sets of new Carbotech XP12 front and XP10 rear pads for sale and I picked up a set cheap.
I'll also need new street brake pads soon and may look into Carbotech Bobcats.
If it works out with my work schedule, I'll be doing Watlins Glen, Monticello, and Lime Rock soon. By then, I expect my ADVAN Neova AD08 tires to be worn out. I do know of a few race teams selling 275 width R1's and R6's that have been heat cycled 2 or 3 times for a very affordable price. I'd need wider wheels for those tires though. I could also get a set of 245 width Koni Challenge slicks that will fit a spare set of wheels I have. Unfortunately, the Grand AM Rolex DP Hoosier slicks are a little too wide to fit my car. They are about a 315 and they will fit fine on the rear wheels, but clearance becomes tight if I go above a 285 width tire on the front.