I don't think we should even include mods in bench racing. Once those enter the arena, only timeslips or direct competition have much validity. Statements like: "I can easily pick up (insert necessary number here for sake of argument) hp with a chip, intake, exhaust," are good for forum arguments, but unless you buy the components, put them in, and dyno the car, you don't really know if that's true for the particular parts, installation, and engine that you have.
So far it seems like the Mustang and Challenger are very close, and would be a driver's race.
Camaro, based on weight/hp and hp/$ looks like the winner by pure numbers.
But I only care about that a little. The Challenger is just a much cooler car.