The rules are a mess / non existent and you basically need to have different setups, depending on where you race. I can see why there is no growth because of this, causing some FE racers to leave the class / not attend races, and good luck trying to explain it to the new guys..
For example, are you good at rewinding inrunner motors? Kinda ironic you have to be able to rewind a spec motor to compete in the class. Can’t use a box stock 3660 in some places, but a 36x56.5 is ok with internal parts from a 3660 with more copper added to the windings. It’s like completely modifying the internals on a Zenoah 26cc, and still being allowed in in the Stock Gas class, because it’s still a 26cc case.
It’s not hard to develop the rules, copy Namba P- limited rules for continuity and promoting racers to travel between the Orgs. Then not allowing internal modifications, so you keep the specs and output as it was manufactured..