Any of you ever used the shorty spark plugs. My 440 has Indy Ez heads and hookers headers. There are a couple of plugs that come very close to the header (on pass side). I was thinking of trying a shorty plug. Are there any performance issues and can they be mix matched with the other plugs, as long as they are the same heat range? Oh, by the way i have about a 10.8 comp.engine.