Hi,<br />I have a 2003 model 150hp Optimax manufactured in 2002. The standard plug is a NGK PZR5F-11 running a .40 in. Gap. I purchased some new plugs some time ago for a 2003 model which are IZFR5G. <br />Looking on the NGK web site these IZFR5G plugs are for 2003-2005 models and run a .31 in...