How about the other side of the equation. The cars that are very very hard to beat.
For example the ITA CRX/Civic Si's. A well built miata can beat them and of course the driver always is a big factor in any race that you look at, but what other cars are beating the Spec Honda ITA recipes.

Saturn SC2's, some of the Nissan products?

Of course I think a great car for the class is the Focus or Mazda 3's. Especially since now you can build a Mazda 3 with the 2.3 for the class. You are already starting out at IIRC 160HP stock.