[Si Coe]

Lots of clubs run spec classes with homegrown rules successfully, but thats not at all the same as doing it on a larger scale.
Club level spec classes exist just to save money and reduce speeds. Likewise whilst they may be popular they are always seen as a 'lower' class and strictly at the one club. Consequently there is little to no point spending big money to win. You could get a slight edge at York buying 50 Saturns, testing them all and only running the best ones, at Southport making sure you have the latest and best 10.5 and for both some super spec batteries would help but why bother? If you aren't interested in keeping it cheap you might as well race Mod.
However the moment it gets bigger than club level that all stops. Spending big money becomes worth it at larger meetings.

Spec classes only work when there is a commitment from all parties to keep it fair. As soon as people start looking for an edge its essentially failed. The bigger the meeting, the sooner that point is reached.