What if 2015 IRS can be retrofit into a S197?

[Grandpa]

I personally don't see a need for it. The aftermarket available to Mustang owners is so vast and full of components that can make the SRA suspension handle very well that I don't see a need to put a very heavy IRS in it that might/might not work as well.

Hell, Corvette is still using a transverse rear leaf spring type set up and it handles better than some super cars that cost 3 times as much with really advanced IRS systems!