Does anyone know for sure whether the performance between wtcc 2007, 2006, stcc2, and stcc are compatible to run in a single championship? I race on another site also where we currently run a championship with 07 and 06 cars but I'm looking into the possibility of running more manufacturers for the next season... I have worked out the power to weight ratios of all the cars and they seem to be comparable between the above classes... Am I missing something such as tyre grip? Is it the same or do different classes run different spec tyres? The other option is to run the ssr2000 mod which has updated and equalised cars but we are aiming to not use mods in our official championships if we can. I have deliberately not named the other site so this post shouldn't contravene the rd rules. Any advice or insight welcomed.