[Bspec79]

Hi all,

I recently installed an MPE exhaust on my 328 about a month ago. I've clocked up close to 2k km's.

Although it's probably still breaking in, I've noticed that carbon is only building up on one exhaust tip whilst the other remains pretty spotless.

Is this normal? (Pic attached)

I can't say I've really noticed any crackling or burbling sounds that others talk about either. Does it need to break in more?

[mdavis12]

that's normal. I don't have a MPE. You are seeing build up on one tip because there is an actuator that controls the other. it is not always open. usually open at startup. You can hear the click when it opens and closes.

[Bspec79]

Originally Posted by mdavis12

that's normal. I don't MPE. You are seeing build up on one tip because there is an actuator that controls the other. it is always open. usually open at startup. You can hear the click when it opens and closes.

Thank you.

Yep, I've heard this click as it opens and closes.

What's the purpose of this actuator? How does it decide when to stay open or shut?

[DG20]

Originally Posted by Bspec79

Thank you.

Yep, I've heard this click as it opens and closes.

What's the purpose of this actuator? How does it decide when to stay open or shut?

The valve opens up when you put it in sport or sport plus mode. There is this little mod you can do called the golf tee mod that keeps the valve always open but i just unplugged the wire while the car was in sport mode and it always stays open!

[mdavis12]

Originally Posted by Bspec79

Thank you.

Yep, I've heard this click as it opens and closes.

What's the purpose of this actuator? How does it decide when to stay open or shut?

When you read through forums, some people say the valve mechanism helps increase back pressure. Other say its purpose is noise reduction. The noise reduction theory seems to be the one most people agree with. Hope this helps.

[mike@x-ph.com]

Carbon building is normal as mentioned above
As for the burbling, get catless downpipes