I put lighter wheels on my 2017 Gt 350. Stock wheels are boat anchors (60 plus pounds with tire) The p 51 wheels knocked off 8 pounds per corner. Acceleration much improved ( more torque in lower rpm range starting at around 2300. Keeps warranty intact. Those wheels are the closet in weight (23 lbs front and 22 lbs rear) compared to the R’s wheels. Great question.
I get most of my replacement wheels at 4WheelOnline. I'm pretty satisfied with their selection of aftermarket wheels especially when you need one to accommodate special tires like winter tires and mud tires.