Recently I've been thinking about doing an exhaust cutout but I started thinking about ways to make it better. I have an idea that is purely concept and I have no idea if its possible or worth attempting so now I bring it here in hopes of hearing from more knowledgeable people.
Add a y pipe/diverter valve that can send all exhaust down one pipe or the other electronically actuated.
Y pipe split before 2nd cat
One pipe runs to stock exhaust for daily driving
Other pipe runs pipe with only one muffler (if needed for sound) then runs exhaust back to stock exit piping after stock muffler
Make diverter valve actuate based on sport mode button being active and have a tune in ECU for this piping setup that activates in sport mode.

Does this seem possible at all, is it remotely worthwhile, or am I a crazy loon dreaming a big awesome dream?

 

You're going to have a tough time just fitting another muffler in the exhaust tunnel next to the factory exhaust. There isn't a ton of room in there even if you were to use an aftermarket bullet-style muffler. Your best bet would probably be a cutout right before the factory muffler as there will be space back there to make it work.