I went to Thunderhill a few weeks ago and got to play around a bit during a private track day. I was on my Michelin Pilot Super Sports 300 TW tires. I was running 2:06 - 2:07 laps without traffic. I left a lot of time out there as I was having some brake issues. I was noticing under heaving braking I was loosing brake pedal and it was getting worse each time. I only ran three sessions in the morning. At lunch I discovered the brake switch in line for the tail lights had a huge leak. Brake fluid was coming out of the switch under pressure. That ended my day. If you notice in the video, I was giving up way too early for turns 10 and 14 and everywhere else just a bit too much. I would hope I had another 4 seconds I could shave off if I had a solid brake pedal.
I have only been to Thunderhill 2 times. I plan on going back in a month or so to get where I want to be. I will also be on the Michelin's again.
James, if I was on the Goodyears, I would be sub 2:00 no problem, even with the brake issue.
Brian