To the OP, what psi (cold) are you running?

32psi

I love my S04 tires. When I bought my Z it had some really crappy Kumho Ecsta tires on it. The transition from the Kumho to the S04 was amazing. The temps around here are in the 40's and while they have lost some traction, they still are not bad.

I think I will try a set of RE11 next just to check them out.

I've been on the dragon on my bike but not the Z yet. That will most likely happen this summer. What a ride!!!!

is the SO4 the replacement for the RE050A? read that on Jalopnik (?)

I would consider them an upgrade from the RE050A.

Tire Rack is your friend when it comes to doing tire research. I always read the reviews before buying tires.

The S04 tires that I have were purchased from TR and a local installer mounted and balanced them. The left front tire had a flat spot on it that the installer noticed. He recommended that I drive the car a couple of days and see if the tire would get better. It didn't. I called TR and they sent me a replacement and had UPS pick up the bad tire from my house. Fantastic customer service. They even reimbursed the installer for the remount and balance.