https://www.youtube.com/watch?v=YvqP7Zbs5Oo&t=1409s
Not that this directly applies to you but I am running a GTK Active muffler on my 914 and made a 2 part video on it. It is probably my favorite modification on old #6. I had the pleasure of driving to Rennsport 7 along side Leafgreen Matt and we made sure to open the valves through every single tunnel from Illinois to California, it was pretty epic. As a dude who made a living fabricating race cars and industrial equipment in a past life I can guarantee you that this is one of the bet built mufflers you will find. I personally am really happy with the sound and there is zero drone in my car.