I think the "spirit" of the 540 class is for youngsters, beginners and old farts who can't see! (no offence meant
).
At the last AGM a motion was passed that if you win the 540 championship you can no longer enter it. Policing it would be tough as time seems always so short and as has been pointed out a 17.5T car can fly just as fast as the mods. As I said it's the "Spirit" that counts.