Few days ago I was able to do some test driving on the highway. Temperature was around 50F when I started my test drive. First the tires felt little bit hard, but after they warmed up, they softened nicely and provided really good grip. On highway my car went really straight, like a train. Steering feedback was also better than with my old tires. My initial feeling about tire noise was also correct. zLines are little bit quieter than P Zeros on the highway, but just a little bit. In my opinion this is still a good result because zLines are 20 mm wider and tire profile is also smaller.
I also tried one full throttle acceleration. I have one very safe and legal spot to do this. I had second gear in and tachometer was around 4000 RPM. Engine is making over 440 lb/ft (600 Nm) at 4000 RPM. I fully pressed throttle pedal and car accelerated like crazy. Soon I had almost 7000 RPM on tachometer and I had to stop. During the whole time of acceleration, body of the vehicle and rear end were really nicely balanced. Rear end did not fish tail at all and I did not feel any slipping on the tires, which was very nice finding. I was able to spin my old tires much easier so I can honestly say that these new zLines have much more grip.
The most important goal is now achieved: I have more traction on the rear wheels! ;)