David,
Last weekend we ran at Motorsports Ranch. Tony Lee and Donato Forte were there to decide the 2002 title. I'd bet money that both of them are legal. But the fastest guy there, setting a new lap record, was Greg Kennedy. And I'd bet my logbook that Greg is legal.
If there's cheater cars in the pack, I suspect they are midpack. There isn't that much to gain, seat time is where it counts.