I've just done my, 2000 Boxster with 63K, plugs and I regretfully went with NGK 2 prongs. I could notice that second and third gear doesn't push me against my seat like it use to. Although, I noticed that I got around 120 miles with a quarter of a tank.
As far as gapping goes, I've not seen anything about gaps and I would say it'll be a bit hard to move them prongs especially the 4 prong plugs. I didn't order enough rings so I'm going to order some more and do them (can't believe an O-ring is 4 bucks each).
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S3adrag0n
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