NGK Plugs should be called NFG Plugs :( Those plugs are crap especially after being in saltwater. Go with Champion or AC Delco Iridium Plugs for the best if you want to spend the money. The Iridium's are the best on the market but are around $10 and up each.
Here's the ones I put in my Corvette and they made a 100% difference in the running of the car.
http://www.densoproducts.com/results...artNumber=IT16
