[mg711]

Does anyone have experience with the Valvetronic axle back? How well does valves closed do at keeping it quiet vs being open?

[B58]

blacksapphire440i

[mg711]

Originally Posted by B58

blacksapphire440i

I ask this guy?

[B58]

Originally Posted by mg711

I ask this guy?

Yeah I think he has the valvetronic axle back.

[mg711]

Originally Posted by B58

Yeah I think he has the valvetronic axle back.

Okay

[blacksapphire440i]

Originally Posted by mg711

Does anyone have experience with the Valvetronic axle back? How well does valves closed do at keeping it quiet vs being open?

Sounds quieter than stock (even quieter with a stock downpipe/high flow dp) even with a catless downpipe.

https://youtube.com/shorts/wMJvC3l2_...PVDJw8yO27-2HU

https://youtube.com/shorts/KeBAihdC9...5CoKd0cgGMxjIT

https://youtube.com/shorts/Uf6pZiU8a...jUl8hxJb8GAIrL

https://youtube.com/shorts/MXOoMl7IS...wIoU9gDxv6rV3O

[mg711]

Originally Posted by blacksapphire440i

Sounds quieter than stock (even quieter with a stock downpipe/high flow dp) even with a catless downpipe.

https://youtube.com/shorts/wMJvC3l2_...PVDJw8yO27-2HU

https://youtube.com/shorts/KeBAihdC9...5CoKd0cgGMxjIT

https://youtube.com/shorts/Uf6pZiU8a...jUl8hxJb8GAIrL

https://youtube.com/shorts/MXOoMl7IS...wIoU9gDxv6rV3O

Cool thank you I’ll check it out

[mg711]

Originally Posted by mg711

Cool thank you I’ll check it out

Wow that’s actually very helpful bc it’s the same setup (exhaust and engine mods wise) that I’m hoping to do. Thanks for sharing

[mike@x-ph.com]

Originally Posted by mg711

Wow that’s actually very helpful bc it’s the same setup (exhaust and engine mods wise) that I’m hoping to do. Thanks for sharing

Once you get it, please share your feedback

[mg711]

Originally Posted by mike@x-ph.com

Once you get it, please share your feedback

I will for sure. If/when I get a 340 I’ll make a thread reviewing and discussing my progress. Just depends on if I can keep up with the payments on my golf and then the plan is to sell it and use it towards the 340

[mg711]

This might be dumb question but the mppsk cat back just hooks up to the cat back correct there’s nothing in between

[eff32fl]

Originally Posted by mg711

This might be dumb question but the mppsk cat back just hooks up to the cat back correct there’s nothing in between

Correct both resonators are deleted.

[mg711]

Originally Posted by eff32fl

Correct both resonators are deleted.

Okay thanks

[eff32fl]

Originally Posted by mg711

Okay thanks

No prob.

[mg711]

So I was looking around and I found you can just get the mppsk muffler (basically and axel back). If I’m looking at it right it only requires an additional purchase of the wiring harness.
This got me thinking, if I get a 5in dp could I just run 5in all the way back to the mppsk “axel back”? Note this would be a custom fabrication mid section. The idea in mind is 5in pipe from dp to muffler with a about 6in length section change from 5in to the oem 3.3 in or whatever.

Links for the mppsk-
“Axelback” https://www.getbmwparts.com/oem-part...b3J5IFBhZ2U%3D

Wiring harness https://www.getbmwparts.com/oem-part...er-18302414899

[Skyhigh]

The MPPSK exhaust has a larger diameter pipe than the stock exhaust! Don't remember what the diameter was though (3" instead of 2,6" I read somewhere now after a quick search, but uncertain). So bear that in mind if you are planning customisation.

And yes, for the electrical part you will need a new wiring harness for the valves to be controllable.

[mg711]

Originally Posted by Skyhigh

The MPPSK exhaust has a larger diameter pipe than the stock exhaust! Don't remember what the diameter was though (3" instead of 2,6" I read somewhere now after a quick search, but uncertain). So bear that in mind if you are planning customisation.

And yes, for the electrical part you will need a new wiring harness for the valves to be controllable.

And what about the diameter of the mid section? If I’m going like 5in all the way from turbo to muffler is that fine or should I do 5in dp 4in mid section

[Skyhigh]

It is larger diameter than the stock one for the entire length, from cat to muffler.

I understand what you are thinking of doing, just not sure why... If it was me, I would just buy the entire MPPSK exhaust (which again is already larger than the stock) and move on to other problems in my life than putting together an exhaust midpipe myself
You can put a 7" pipe probably, but what good does it do if you have a bottle-neck down the line....

The MPPSK is very well dimensioned, even for a tuned B58... You will not gain anything from going larger, especially not if just the mid-section.

[mg711]

Originally Posted by Skyhigh

It is larger diameter than the stock one for the entire length, from cat to muffler.

I understand what you are thinking of doing, just not sure why... If it was me, I would just buy the entire MPPSK exhaust (which again is already larger than the stock) and move on to other problems in my life than putting together an exhaust midpipe myself
You can put a 7" pipe probably, but what good does it do if you have a bottle-neck down the line....

The MPPSK is very well dimensioned, even for a tuned B58... You will not gain anything from going larger, especially not if just the mid-section.

I was thinking in terms of exhaust tone if having a wider mid section would change the tone compared to a 5in dp and the full mppsk exhaust

[mg711]

I guess my main question is this- would having my exhaust be 5in from the turbo and reduced at the muffler to 3in be too big and the gasses not being able to escape? If it’s not too big would this deepen the sound?

Now you may ask why. Because I want to make the car unique to me. If successful hopefully will inspire more variety of exhaust systems for example how go tank is very popular for their f1 car inspired svj exhaust.

[Skyhigh]

There is only one way to find out. But even if you do it - how would you know whether it is deepER than full MPPSK without having a datum...

[mg711]

Because isn’t wider diameter generally deeper tone ignoring sound level