Seems that the pipe has a flap in its end . Looks funny to me. I wonder whether it has been built in for more power or for sound design . Got this photo from

http://www.auto-motor-und-sport.de/d/68028
(unfortunately German language)

I am not quite clear about whether using such aids can be considered a technical improvment or are a curiosity of "over"-engineering ...

Have fun!

Regards

Jack - E61

 

It's there for sound muffling - closed during normal cruising and opens up in the upper rev-range. It operates on a vacuum.. some E46 guys take the little hose off the 'switch' and tie it up so that flap is always open, gets you maybe a deeper sound on part-throttle. It has nothing to do with the ECU(at least that's the case with my 330). You'll see all the parts to it if you crawl under the car.

 

That is interesting that it is after the muffler. In the previous posts, it was before the muffler, at least the one's JDN had. Based on the picture, they should have modified it, or it is revved up to have it open for the picture??

 

It's open in the pic - high RPMs. It's closed at idle and really anythin below about 2,000 RPMs. There are a couple of posts here about it - search for exhaust. Bunch of folks are wiring it open, as an inexpensive exhaust upgrade.

 

Here's the thread that discussed the exhaust valve earlier...

 

Even in the 530d with the straight pipes i think that is something in there because i noticed that the left pipe is getting a different coloration (lighter) from the right pipe.
Could it be? I didn't knew that the 535d had that system and in the 530d i can't notice nothing from outside but the coloration in the pipes is different....