If you race on CTRA 1 you notice most of the drivers use the XFG, but then you will see a good driver in the XRG winning the race. RWD is better, clearly. In all FWD cars the engine is over the front wheels, so again, it's asking too much but not only that, but when the engine is mounted over the front wheels, the rear wheels have nothing to do literally, theres almost no weight, infact, you could add rear weight to balance the car 50/50 and you'd probobly be faster, the only disadvantage would be under braking. Still, it's been clear since the beginning of front wheel drive that the maximum ammount of horsepower is around 200bhp anymore than that is just insane, rear wheel drive cars clearly can handle more power better anyway.
Imagine the Carrera GT take the engine from the middle and put it to the front, then swap the drive chain to power only the front wheels, and it's going to be probobly, the worst handling car in the world, ever made.