Takai (racing) has an ad for plugs in SSB, claim 2hp and 2tq. Haven,t checked cost . Their coils are good I hear.
Don't know about others but, I have never checked clearance on a spark plug on any of my vehicles and never had an issue. I just replace them when it's time.I dont think I'd buy these...mainly because theres no way to adjust gap setting to keep them in spec...in general, all the "multi-prong" plugs are gimmicks, most dont really offer all that much of a gain, other than a slight increase in lifespan if you're not adjusting and checking gap settings.