Are there any aftermarket options for exhausts yet?

Or is the exhaust layout the same where I can utilize the exhaust systems from the previous Panameras before the refresh?

 

It should be the same. No reason for Porsche to change the layout. Mid model refresh is mostly cosmetic.

 

Different engine and exhaust system for the 2014 stock.

The 2014 is a V6TT, and the stock system is a butterfly valve system. The valves open and close for more power and better fuel economy. So I'm wondering if the old system mated to the V8 still can be used...

 

I assumed the V8 models since the engines are carried over. My bad.

The PSE uses the butterfly valve system as well so any aftermarket that uses it should works fine. The akrapovic installed on mine has the valve system. I just have to connect the vacuum line and it works fine.