The manual states to not run my Honda four stroke 90 HP (2001 model) for
more than 5 minutes at full RPM. The throttle actually backs off
automatically after about 1 minute of full RPM action.

Anyone know if running at full RPM can really affect the engine? When I have
14 people on my 25 foot Bennington pontoon boat, running on anything but
full RPM is slow (below 13 MPH according to my GPS) (especially when I go
against the current on the river that I am on).

The reason I bring this up is that when I use my Honda lawn mower to mow the
lawn, that thing runs at full RPM from start to finish, which is sometimes
hours - the mower has been working like new for the last 3 years.