M5/M6 exhaust flap mod

[cogsy80]

My question is about the free exhaust flap mod that can be done on the M5/M6, by forcing the 2 exhaust flaps open (1 either side) in the exhaust back box. There are plenty of video's and posts about how to do this, but my questions is about why they are there in the first place.

Also, what effect if any it has on the car by having then permanently open.

Please excuse the bad picture as it is quite a hard area to get a good photo of without having the car jacked up.



My understanding is this valve is opened by a vacuum at around 3500rpm for increased exhaust flow/noise, so by fixing these open you just get a bit more noise at low revs.

It does work, but not sure of the effect on the car and why BMW would have them fitted....

[cogsy80]

I did notice the drone at motorway speeds the other day, but there definitely is a better sound at idle/low revs..

That exhaustMeister might be the ay ahead, to open and close as required

[cogsy80]

M5 London said:

It works well !

Also when in the off position it simply reverts to the BMW stock setup (so valves open and close as per factory specs).

When switched on via remote, the valves are permanently open, until you switch off via remote or switch the car off and when you start the car up again its back to factory spec...

I think I am over explaining this....

Where did you buy it, all the eBay links are coming from America?

[cogsy80]

M5 London said:

I liked the idea of having the ability to open and close them at will and on the go, so I went for an Exhaust Meister gadget.

Very easy to install.

I have a remote fob in the car and open and close them at will with a touch of a button.

Essentially when cruising in a high gear on a motorway it does drone when open, so I can simply close them, and it makes a difference. Its quite a subtle difference and people who have them permanently wired open probably don't realise but it does make a difference.

BMW designed them to open and close for a reason and I think its very much NVH based.

Did you install the Exhaust Meister yourself? Mine has arrived today, just wondering if you can give me some pointers on location, before I take the whole boot apart?

Thanks