Originally Posted by desertbird

Well, I would guess that the change in plugs and subsequent leakage would be due to a tapper and length issue between plugs. I would only trust that OS has the same tapper as GRP, based on the measurements proven in this thread. No one, that I recall, has proven an OD plug to fit the same tapper or length. Maybe I just don't remember correctly, but I thought Novirossi and OD were interchangable, and that novirossi didn't fit GRP head period. I could be wrong, it's been 5 months since i've researched. So please do not take my word as gold, and feel free to correct me if i'm wrong. Hell, running that P3 is probably why my GRP had a sucky bottom in my truggy.