time to replace the plugs, but want to know what anybody else has tried, anyone try the NGK? has the Denso's in it now.

NGK's in many Mercury applications will give the absolute best idle performance and prevent carboning problems. Things may be different now with the new ECM's. I put a set of Split-Fires in and it took all season to figure out why the engine was acting up. Split-Fires are a no go Houston.