[chino@wiesbaden]

I installed my MPE about a week ago and been driven it for about 500 miles. Today, after a long drive I noticed that the right pipe have black residue and the left one doesn't. That when I slightly touched the left pipe to see if it even hot and it's not it's actually cool. I start the car and also realized that the air are only come out of the right pipe, barely any from the left. Did you guys with MPE experienced the same, or I must did something wrong? I have a 2013 328i btw.

[BeachsideF30]

God that's really strange, did you call the dealer?

[chino@wiesbaden]

No, I didn't call them. I figured that I ask here first since a lot of ppl have installed the MPE. I'm thinking that either the MPE designed to have air flowing out of one pipe or it's still under the breaking in period.

[BeachsideF30]

So you mean to tell me when you start the car you realized that the air only comes out of the right pipe, barely any from the left. This sounds like a severe design flaw to me, then why have 2 pipes????? I wonder why the right tip of 335's is always darker too lol

[focal]

yes, I noticed too, but having burnt my leg once on the tips, I'm not touching them

[Tim@codemybimmer]

It's probably just the butterfly valve that's installed in the left pipe. Only opens on cold starts (it reverts to open when you turn it off I believe) and when you're heavier on the pedal.

[Tony M]

I have the MPE installed. Not surprisingly, the behavior of the butterfly valve is the same as it was with the standard exhaust. In sport mode it is always open. In comfort mode, it opens at higher revs -I haven't checked exactly, but revving to about 2500 to 3000 seems to open it. I haven't specifically checked with the other modes, but I'm guessing eco-pro and sport+ mirror comfort and sport respectively.

Although the exhaust seems to be at its loudest with a cold start in comfort mode, the valve is actually closed at that time - not what I expected from some of the posts I've read.

[Rick4345]

Nothing to worry about . I've had mine for about a year. It's from the butterfly on the outer exhaust closing. It opens up about 2500 rpm. Just get a good metal polish and everything is fine.

[chino@wiesbaden]

Thanks everybody! I feel pretty happy that it's not because I did something wrong when I installed it.

[BeachsideF30]

What a relief