Rabbit you never fail. The AMG tune works perfectly. On its own struggles up the climb, but in company, it keeps with the best of them. I have bought and tested the Z1 and can confirm it does 300mph easily, but again on its own it struggles. As do ALL the cars. Unless your using TZ3 H13 ETC, but they also need tuning in the right way, or they simply don't work how you want. This is the principle reason GT6 allowed BOOST and STREAMLINE, to allow 80,70,60,50,40 and 30 year old cars to compete with the modern day beasts. Goodnight my friend.