F1s aren't bad when new, but they and other cheaper tyres 'go off' quickly. The more expensive tyres resist the hardening caused by constant hot/cold cycling. It's the same thing that causes all the plastics and rubbers in the engine bay to become brittle over time.
Anyway, PS4s, amazing tyres. Had F1s on previously and they were very easy to find the understeer limits on, but the PS4s need pushing VERY hard to understeer.
I keep hearing good things about the Yokohama AD08R, so another option to look at.