I just switched to the Rapidfires and will continue to use them because I PERCEIVED the side of my boat to be a little cleaner.[I have side exit exhaust] This is just an opinion...the boat has run as well or better than it ever has...is it because of the spark plugs? Maybe not, maybe. They are of nice quality stainless and I just don't see a company like AC/GM risking their reputation on "snake oils"....I think they might be a small benefit to conservativly timed naturally asperated motors.

I heard they work great I did not know why but if there side gapped thats cool

I'M Talking about the ACCELS not rapid fires

Adivanman did the correct thing-ask the manufacturers. Boats need a plug that will warm up quickly to help prevent fouling at idle during warmup. Cup cars get special treatment so they can go only for power. Boats need EVERYTHNG!!!
Extended nose plugs heat quicker. Cutting the ground electrode off at the center of the positive electrode with cutters will make a few more horse, but the tip will burn off quickly. Cutting the ground electrode off with a Dremel tool or similar, does help and lasts. This is a small gain and I would have to think hard if it were worth the effort.
Strange alloys, multiple grounds, etc. are pretty much gimmick for performance. Platinum lasts a very loong tme, but doesn't make as good a spark.

yep mr 1500 is right the platium is designed to last not perform and will be down a few horses ,

the ground strap trick I like becuase it will make a hotter flame and help keep the transom clean cheap ,,plus h.p. too

1500 get to work you bum