Just thought I would share my experience and perhaps assist others going the same route.
Aircraft: RANS S6 with Jabiru 2200A engine.
I had a slight "crackle" when receiving and transmitting on my radio (ATR500), so I decided to fit resistor type spark plugs. The 2200A engine calls for NGK D9EA plugs and I decided to fit NGK DR9EA plugs. The engine ran fine until full throttle for takeoff where the engine showed a distinct lack of power. As I had a nice long runway there was no problem getting airborne but nevertheless decided to circle rouind and land.
I then changed back to the original plugs and full power was attained for takeoff.
I can only surmize that the extra resistance in the DR9EA plugs was just too much for the ignition system.
I've added this to the RANS S6 section aswell.