I would be doing 70+ in a 55 feeling like I as doing 60mph. I got SO many tickets that it just wasn't worth it anymore. The headgasket issue was just a simple change to a HKS Multi layer and torque the headbolts down 13lbs past what the factory suggested. They would back out and allow the head to "flex" under boost, which lead to warped heads and blown gaskets.
People say life isn't measured in the ammount of breaths you take but the moments that take your breath away... My Z takes my breath away every time I'm behind the wheel.