Spec Miata is a wicked class. It's not untypical to have a significant amount of contact, especially with the front runners, in a single race. Furthermore, there's always some "interesting" tuning happening under the hood whereas it's not uncommon to find a "stock" 1.6 Miata putting down 120+ HP to the wheels. That's not to imply that there is cheating involved, but some very crafty mechanical work, tuning, and/or engineering to get the engines to a dead nuts stock tolerance, weight, etc.