Sports sedans need to be equal, no matter what brand and model of motor is used.
Not trying to sound rude but your logic is floored.
The cars will never be equal, given that the rules and the interpretation of them is so open let alone the mechanical and physical differences of each car, that is what makes the sport sedan class so good!
Look at the series now, Tony just dominates and he too runs a Chev like the majority of the front runners so there isn't even equality among the Chev powered cars.
Equality doesn't exist in Motorsport, while the engineering aspects of the car are totally crucial the budget will ultimately determine where you end up on the grid. The cashed up competitors have the ability to spend more time on development, track testing, use better and newer parts and maintain their cars so they don't break parts. The guys with little or no budget get on track when they can afford it, use whatever decent parts they can get their hands on and only replace
parts when they break. That is the reality of the situation.