As I see it, it’s a decision on what you want the TBO class to be, at the moment the fxo is just way to strong, there is absolutely no race between the classes as it is right now, if you want a versatile TBO class where the different character of the differences in the cars 4wd, Rwd and Fwd, it need to be balanced out.
So if you just want a Fxo train then doesn’t call it the TBO class, for that it is not.