I'm a big supporter of NGK myself, been using them for almost 25 years, at the race track you'll see guys almost exclusively use NGK plugs, The higher the number the colder the plug with NGK. We've used as cold as #10s in the full prep race engines, we use #8s in the SCCA limited prep engines, and I think that is a good choice for you car on the race track, yu can get away with the projected tip as well until you get way up there in compression ratio, so I would suggest Scott a BP8ES, you can spend more money on the EV plugs, but they never showed us even 1 horsepower on the dyno, save your money and buy the ESs