I'm not an aero fan especially on a streetcar because you hit things and damage the aero. Even on track when you spin off you tear off splitters and mounting points. It can get real expensive. That's why in the amateur in trenches you will see lots of plywood splitters from Home Depot Racing Supply.
Have you optimized your suspension? Maybe you can get gains there. I'm amazed 95% of Mustang people have no way to adjust ride height and corner balance their cars. When I bought my 2019 GT to make a race car I was shocked that my S550 lacked these important features. Thankfully, there is an active aftermarket to the rescue.
Then If you have spent to optimize your suspension the new aero can change all of that. So if your areo is really working then your wallet is going to feel it.
Finally, I agree with Blacksheep. It depends...
Have you optimized your suspension? Maybe you can get gains there. I'm amazed 95% of Mustang people have no way to adjust ride height and corner balance their cars. When I bought my 2019 GT to make a race car I was shocked that my S550 lacked these important features. Thankfully, there is an active aftermarket to the rescue.
Then If you have spent to optimize your suspension the new aero can change all of that. So if your areo is really working then your wallet is going to feel it.
Finally, I agree with Blacksheep. It depends...