Under FAI rules for CL speed there's only one class and that's F2A which is for engines up to 2.5cc (meaning you could enter with a Cox .049 if you wanted to
). Line groupers have been banned for a very long time and twisting of lines is also banned as is covering the lines with any kind of liquid or coating material intended to reduce coefficient of drag. There's also a minimum seperation of lines at the leadouts and handle. Pull tests are 50G and have to be repeated 3 times.
Individual countries of course can have whatever events they like for different engine sizes but any claims for a world record won't be recognised by the FAI otherwise someone could claim a record for a steam powered speed model
. Ya gotta draw the line somewhere.