I think I got detonation on my V9 as the weather changed to warm a few days ago. When sitting in stop and go traffic and the engine gets real hot, an ugly metallic noise that sounds like detonation results under heavy load. In EU, we have 95 and 98 octane fuels, which are roughly equal to your US 90 and 93 (this is the ROI vs MOI vs AKI index, look it up if confused). Anyway, I was using 95 and switched to 98 now, will be observing it on the hot days to come. What are your thoughts and experiences, maybe others noticed same thing on the specific 853cc V9 engine?