Cayenne Turbo 2005, Fuel Question?

Lower octane really doesn't mean a thing. Explanation---> All octane ratings really have the same amount of heat output, so they create the same amount of power. The only thing 98 does instead of 95 is it reduces your chance of sparkknock. You don't need any octane booster. You're fine. Octane booster is a bottle of wasted money for this case.