Would this be the one on the speedboat in Dorset ? I think a customer of ours went to look at it and left it there...although mainly due to the trailer which needed work. It was advised as 2006 (as most seem to be due to the EPA sticker confusing owners) but there will be the age on the plate above the transom saddle, under the front of the lower engine tray. My bet is late 90's
I'm not a huge fan of Honda, the older ones seem to age ungracefully. One engineer I spoke with called it the Paracetamol - they dissolve in water... Mechanically they are very strong though.
The new ones are up there with the best of them though and I can think of at least one person on here who can give you better detail on them, provided you've not considered E-TEC