I haven't changed the spark plugs for this motor since I bought it, any recommendations on better performance spark plugs and what's the gapping on these motors?
None. Merc uses surface gap plugs for performance issues under certain conditions. Surface gap plugs have no electrode that you can move to adjust the gap. I have run SG plugs for 10 years on my 115 hp tower of power with stellar performance......Hence no reason to change them.
Most of the V6 motors use a surface gap plug, no adjustment is possible, it is built into the design.
Often NGK BUHW is listed but it should be verified in the service manual or NGK Catalog as there are a few difference heat ranges and you want to be sure that you use the correct one.
