"GAIN 5 HORSEPOWER" - comment on this please

[yebo]

albert b,

indexing the plug means marking the spark plug where the opened side is (or opposite the ground tip). then when the plug is installed position the open side towards the intake manifold. to do this when the plug is already hand tight in the spark plug hole tighten it so that the mark faces the intake manifold. good for 1hp gain daw sabi sa site.

[niky]

Actually, it's common sense... I can't believe I haven't done it myself.

It could also be why people complain that 4-tip plugs feel like crap... as there's always a post disrupting airflow past the tip no matter what orientation it's in!