Well, I did it. It took about 3 hours to take off the rear plate. I'm not sure it's worth the effort. When I first started it, me and my wife looked at each other in puzzlement. It sounded the same. Only when I manually opened and closed the flaps at different rpm did we notice a subtle difference. It's a bit more "throaty", but definitely not dramatic.

I'll post some pictures a little later on today.

 

What about your warranty, and DME read outs?

 

Warranty expired and cannot be renewed. DME may not know, but I'm not positive.

 

as long as the lines are plugged there is no difference.

 

Are the flaps driven from the Speedometer or the DME.

It makes a huge difference.

 

They are controlled by the DME. But it's a one-way control system, other than the DME looking for plausible electrical signals from the exhaust flap vacuum switches. As far as I can tell, the DME does not know that you unplugged the vacuum lines from the exhaust flap solenoids as long as you plug the vacuum lines to simulate a connected exhaust flap solenoid.

 

I decided to re-connect the hoses. The sound difference was pretty small, and I'm not certain if there may be a low-end power loss with the flaps open all the time. It seems Porsche has a lot of programming for the flaps, more than would be expected for just sounds level reasons.

 

^
Good move! And, pretty astute observation re the programming and monitoring.