Porsche GT2 Dyno Tuning [Video Included] Definitely a car worthy of a track tune, the Porsche 996 GT2, being an absolutely incredible car even stock, but the customer wanted a little more power on California 91 octane (not known to be a great fuel) and even more on 100 octane. Some o the drawbacks of living in California is the fuel quality, being a 91 octane fuel and not even a good 91 octane, the octane rating and quality are just not the same as the east coast and definitely not even remotely close to the level of European fuels.