Kinda pricey but nothing on a boat is cheap. I installed these in my 96 Mercury 115 HP 2 stroke outboard, replacing the non-resistor version to rid myself of a ticking noise coming out of my 6x9 speakers at idle. Sure enough these did the trick. No more tick. I also went 2 mph faster than before with the same load but it could have been the wind. It definitely didn't hurt the performance and it sure did fire up easier. For the $28 I paid for four plugs you can't go wrong. I couldn't even get a good RCA noise filter for that much.