OK, so lets run a scenario.

Your RX-8 will race with the highest deduction for TW 131 and up at a weight of 3005.
And your buddy, on the same tires will race at a weight of 2465.

Assuming that car can get that low, thats a 540 pound difference. FIVE HUNDRED and FORTY pounds.

Now, I know that an ITS RX-7 puts out about 185, and the RX-8 about 214, in IT trim.
So, thats about 30HP more to move the 540 extra pounds.

The RX-8 DOES get 1" wider rims, but.....

My quick sniff test tells me the RX-7 will win at 99% of the tracks.

You've taken the idea, and folded in a cross class equalization. While I admire the concept, it really cubes the difficulty of the concept.

Equalizing withing the class for tires of say 180 is hard enough, but adding multiple levels of tire factoring and THEN adding class equalization is reeeeeeeaaaly hard.

How did you come up with your factors??