for engines with 14 mm spark plug thread. Also for Motorcycles, specially designed electrode for high compression engines
the tuning plug. You don`t have to rely on expensive motortesters and false readings, with Gunson`s colortune you can actually look inside your engine, right into the combustion chamber. It doesnt`t necessarily take a college degree to adjust your fuel mixture if you can see the flamecolour, just try it out.