If you access
WWW.tirerack.com you will see sections that provide technical comparisons. There are also sections where people post their experience with the tires. My two cents, I just purchased a new set of sport pilots to replace the Sumitomo's the cheap ass saddled my 22K mile Boxster with. Tires are very important, I would put money in good rubber over intake/exhaust/ body panel modifications. I can't wait to drive my car with the correct rubber, I'm sure its going to be a fork lift upgrade.