I have been using the recommended UREM37HE plug with my electroair ignition and also a UREM 37BY with the magneto on the other side. Both these plugs have the projected "BY" style electrode. I recently noticed that the Lycoming SB1042AC shows that the BY plugs are not listed as approved for any of the 540 series engines. My engine seems to be doing fine with these plugs, now over 450 hr. Are others running "BY" plugs? Any problems?