It is amazing what these Engines can take with Good high octane fuel. Detonation can easily be surpressed in crazy conditions with high octane as a buffer. JWT is useing good approch for the quality of pump fuel today. Jim and Clark were involved in racing and have done massive testing before they ever got involved with the Z. I also have worked with others that worked with electromotive (nissan's old race team) and they had done extensive testing in these areas as well. Mike Kojima also has an amazing background on the subject and has the same beliefs.