I've bought a lot of tires for my Z over the 19 years I've owned it and most were big name expensive tires. I have a friend who owns a wheel shop and he's advised me to save my money and go with the cheaper brands for the kind of driving we do (rapid acceleration and tight cornering). I've learned that soft tires gives me better traction and handling but I can't say the expensive tires performed that much better and I don't drive 160+mph so I don't need z rated tires.
I hear good things about the sumitomo for the price but I'm also looking at the Nankang NS ultra sport. Check em out and save some coin.
