The place for technical discussions about GA and flying.
Forum rules: Technical discussions about GA only, please.
I, Personally, don't like Champion plugs,- Having said that, their website should list a breakdown of their codes, the first group usually designates thread, reach and maybe electrode configuration, thenumber is usually heat- range ("softer" = hotter, for a cold-running engine or a bit of an oil-burner probably better in a rich-running engine with no mixture-weakening. A "hard, " plug is the converse, used for racing and arduous service where really hot electrodes could glow and cause pre-ignition (pinking) which can destroy a piston in seconds.
Suffix- letters usually indicate special features (RF shielding, inbuilt suppressor- resistor , ETC.
Until you have the code for a specific plug- manufacturer, you will not be able to make an informed choice, just because a particular plug works, doesn't mean it's the optimum.
AIUI, Cloud hound is mainly flying aerobatics. As such , presumably the aircraft is doing short (20 -minute? ) sorties, the engine gets a good thrashing with full power climbouts and plenty of high-energy manoeuvers. A harder (colder) plug , under those circumstances, would be unlikely to foul, but more importantly, would be unlikely to overheat and cause detonation which can melt a piston-crown in a couple of minutes, or less!
Horses for courses! At least instrumentation is available (cht, egt) that an educated pilot can determine a proper management- regime.
In the old days, cars had a quadrant on the steering wheel for mixture and another for timing. together, they can be tuned for the requirements of power or economy, without wrecking the engine or shortening it's service-life.