the only thing you could do is something like the aston, and have a butterfly valve thats connected to a seperate pipe coming off after the cats.
thing is that isn't cheap as you'd need 2, but they could be electronically controlled so you could set the volume, tone etc.
you'd be basically running 2 systems, you could have completely stock, or completely non stock, basically a manifold to outside vents.
or you could set it anywhere between the 2.
but to be hones with the money needed to be spent to do that, your better off going aftermarket. and if i was to do it, i'd only do it to an aftermarket exhaust as it would be stainless to start with.
if you do it to stock, the original exhaust will rot out around it.