2007 Audi S8 Exhaust valve solenoid location
 

Thanks for all the excellent information on this forum!

I plan to mount a exhaust valve remote control, that allows me to either run the stock exhaust valve setup (the exhaust valves are then open from 3500 rpm) or to drive with open valves at all rpm (for enjoying the V10 engine even more). :-)

I have tried to search on internet, but cannot find any information where to locate the solenoid that controls the vacuum to the rear exhaust valves.

Thank you for helping me out!

Right behind back bumper on both sides
 

They are right there after the very last can and where the pipes start to exit the back sill.

On W12's, they stay open if you pull the vacuum hoses, though I understand the S8's may do the opposite. Easy to try.

It seems to vary on the W12, mine fail shut when hoses are pulled, others have experienced this too.

Mine do stay open when pulled
 

...on a 2006.

Ultimately I decided it was probably a performance subtract at the margin so abandoned it. Officially Audi says it was for sound control, but in general on an NA motor some increased exhaut back pressure at low RPM's gives a bit more torque as a rule of thumb. One of the hidden downsides of using a freer flowing exhaust. Since it made only little difference sound wise, I just put it back.

Thanks, I easily found both the soleonid valve and the exhaust valves (see enclosed pictures - looks at bit ugly, so I need to clean the car underneath). I did not try to popp the vacuum hoses yet, but I removed the connector from the soleonid valve. The result of this is I believe that the exhaust valves then are closed all the time (will double check today, but car sounded much less "noisy" at start up). So I guess when power goes true the soleonid valve, at start up and above 3500 rpm, the exhaust valves opens up.

I managed to break both the locking tabs on the cable connector that goes into the soleonid valve. Does anyone know if this can be bought from Audi, and the part #?

I used some bailing type wire to open mine at one point. There is a little hole in the bracket where it attaches to the exhaust. I put the wire through that hole, pulled the valve open and then wrapped the wire around the "arm piece" to hold it open. I then just twisted the wire with a pair of pliers to hold it in place.

I didn't notice that big of a difference in sound and ended up just removing the wire after a couple of weeks. Was very easy (less than 5 minutes for both) and was also really easy to remove.

Would be nice if it had a switch like the sport exhaust on my Porsche was. It made zero difference in performance but the sound was great and always made it seem like you were going faster than you were. It was great that you could make it quiet when you wanted it that way.

I'm sure there could be some coding to turn on/off this solenoid through vcds. Probably just not discovered yet.
I thought about having it wide open 100% of the time also but I do agree with having some backpressure at lower rpms.
Don't worry about buying a new connector, just more of a headache. Saftey wire or zip-tie it back together and forget about it . ;)

Thanks for the tip. I will soon have a solution with remote control for the exhaust, hopefully it will be ready within 4 weeks. :-) When ready, I can post some pictures and tell about my experice with it.

You could check the Porsche forum (Rennlist 996 forum). Many owners there add the sport exhaust to their cars but very few use the vacuum switch and related hardware to be able to manually open and close the exhaust flap. Without the hardware the Porshe sport exhaust just stays open all the time. Their exhaust has the same flap as the S8 exhaust.