Looking at the flexplate it has no weights. On the perimeter of the flexplate it has these square holes ... one ever so often. Another words the crank sensor that mounts to the rear of the engine detects the square holes. I've read about it and they call it the "tone ring".
The OEM flexplates will crack near where the plate mounts to the engine. I've seen pictures of one that has cracked. However the guy didn't state how much power his engine makes to sort of give a idea how much power the flexplate can handle.