I am pretty sure the line groupers were outlawed a long time ago. About the year after they were discovered. The last I checked in about 1980? FAI F2A did not allow them either.There had to be 10mm or something between the lines at the leadouts. Since then they went to longer lines, from 52 to 60 ft. They went too fast for me on 52 ft lines, and I got out, but since then they go faster , and the lap time is still the same. Oh, and I got older too. .4 mm lines , or about .016" is still the diameter for FAI. I believe A speed went up from .020" monoline to .024" or so, and lengthened from 60ft. to 65? because they were spinning pretty fast too.