[Putershark]

• Last I looked at the pump I think it was only 91 octane? I only run either Chevron or Shell fuels due to their superior detergent packages and trust me, that is a lot of valves to get deposits on if one is not careful
• No Honda does not require it BUT these engine ECU's have "adaptive learning / programming" that is a carry over from their automotive units even though the engines (Automotive and Outboards) are NOT built the same as many think they are.
• Hard to hear any pinging on any outboard engine due to not having a muffler on the exhaust systems, but I did hear a engine rap one day when coming out of a partial throttle position going to full throttle position in the heat of summer one day. Here again in Florida, the cooling water temps going "into" your engine are in 80 degrees range for months, so you are not drawing off a lot of heat from the engine block. So if you truly understand what Octane is and does (this may help http://en.wikipedia.org/wiki/Octane_rating), and how environmental factors can can have both either a positive effect (such as in a rain storm) or negative effect (hot dry air) on "real time" octane numbers. It is then easy to see why the engine would rap some and the knock sensor would start backing up the timing to kill it.
• Most times though, the knock sensor that feeds data to the ECU will start backing off the timing in the engine long before one would actually "hear" it... Problem is, you are going to keep putting in more and more throttle to get the same return / speed. Well, we all know what giving the engine more throttle does to fuel burn rates
• My recommendation for everybody is the see what works the best for "your" area and the current weather conditions case in point... I run my Pathfinder (91 is recommended) on 89 grade fuel in the "cooler" months and suffer no ill effects in MPG. But to try to do such in the summer heat (unless is it going to rain almost constant while on that tank) and it will drop its MPG to the point that I am actually spending MORE money at the pump from burning more of the lower grade fuel and the boat is no different... Simple physics really, but one MUST test and track to find what works best for their application and the fuels in their area.
• The cleaner one keeps both the outside and inside of the engine though, the lower it's octane requirements will be.