All the discussion about engines and restrictors and such and such.
The Great American Stockcar Series (GASS) out here has two classes - the 410 and Unlimited. 410 means 410 max hp and/or torque as measured by a chassis dyno. You must run an MSD 6 with your chosen rev limit chip, and the dyno pull is up to the chip limit. Can't change the chip after the dyno (I think they also record RPM during the race to make sure).
So all we need is for each region to buy a chassis dyno and set max wheel HP/TQ for each class! Simple, right?
(I'm hearing snickers already... and it's from me)