Z4 M: Euro section 1 vs US section 1: sound level

[filtercoffee]

Does anyone know if switching from the US section 1 to the Euro section 1 would make the exhaust quieter due to having more cat material? How much quieter?

Context - I have catless headers (status gruppe) with US Section 1, oem resonator. When I run SS Powerloops there is some drone. I've read a few posts that say there should not be any drone with stock configurations, both US and Euro. SS support suggested it might be because of the larger euro cat. I'm trying to see if there's any credibility to that theory. If so I might pick up euro cats. Alternatively, add in a resonator, but I'm not sure I want to do custom work as it might take a few tries to get it right.

[86Zed]

SS support is saying no drone with US/Euro Section 1 AND catless headers? I would find that hard to believe, most of the tone change and volume increase is due to catless headers (of any brand).

In my opinion any reduction from a Euro Section 1 would be minimal and not worth the cost and effort to swap out. The Euro Section 1 is not super easy to come by and requires you to cut into the wiring loom and re-route/extend the O2 sensors.

[filtercoffee]

No they're saying there's no drone with the stock US and Euro configs. Here's the response:

Catless headers do increase the loudness to the US Z4 exhaust setup, this may be the cause of the droning.
However we confirm that the SS Power Loop rear mufflers, when used with the the Z4 M Euro exhaust setup, made by the factory, catless headers and the factory, catted front exhaust section, do not make any droning.
You may want to install a Euro front catted section, or alternatively add a set of small resonators to your stock, US -style front exhaust section.
As an example, here is the link to a setup we offer for another BMW M model.

https://www.supersprint.com/ww-en/bm...lytics.aspx#!/

[filtercoffee]

I'm considering the euro section 1 option at this time because there's on available in the classifieds, and i have an upcoming diff service which requires the exhuast to be dropped anyway so it's convenient.

Regarding the rerouting of the post-cat o2 sensors, that to me seems like a good thing because it'll make the car emissions compliant which should help on resale.

[86Zed]

Originally Posted by filtercoffee

No they're saying there's no drone with the stock US and Euro configs. Here's the response:

Ahh. I would take a closer look at any routing, material and diameter differences between the OEM Euro catless header design and Status Gruppe catless before diving into further modification.

Yes the Euro Section 1 installation and routing is not difficult, just tedious - I completed it myself last winter.

[3002 tii]

Did you throw the SS back on the car? Switching to Euro section 1 won’t yield that much more improvement. I really think you need muffler inserts (similar to what RPi owners do) or add resonators.

I forgot are you relying on software or hardware to pass emissions? If the former, maybe you could just plug o2’s back into primaries and replace the section 1 cats with Aero resonators like the m3 folks.

[Vanne]

pretty sure the Euro section has LESS material in it than the US section, i think you may have got that the wrong way around. on another note, i cant wait to see how your going with your build mate

[filtercoffee]

Thanks for the input everyone.

I didn't realize the status gruppe headers could be louder/more droney than the euro headers due to material/routing differences. 2.25" diameter. 304 stainless steel. They are routed differently.

3002 tii my plan is software but I do want to run some cats anyway. Thanks for the tip re aero resonators.

Vanne, a bunch of forum posts say that the euro section 1 has a physically larger cat material housing (which acts as a resonator) and inside the material is longer (the us material stops shorter). It makes sense because the US section 1 is secondary cat, where as Euro is primary. But please correct me if I'm wrong.

[3002 tii]

Originally Posted by filtercoffee

Thanks for the input everyone.

I didn't realize the status gruppe headers could be louder/more droney than the euro headers due to material/routing differences. 2.25" diameter. 304 stainless steel. They are routed differently.

3002 tii my plan is software but I do want to run some cats anyway. Thanks for the tip re aero resonators.

Vanne, a bunch of forum posts say that the euro section 1 has a physically larger cat material housing (which acts as a resonator) and inside the material is longer (the us material stops shorter). It makes sense because the US section 1 is secondary cat, where as Euro is primary. But please correct me if I'm wrong.

I think the SG headers being louder than Euro is plausible but not a cheap experiment. Did you modify your US section 1 to accept rear o2’s or are they currently plugged into your SG headers?

Re section 1 differences I do believe you’re correct in that Euro has a denser cat.

[filtercoffee]

Agree. I did not modify my US Section 1. all o2 sensors plugged into the SG headers. secondary o2 is ignored via tune

[3002 tii]

Originally Posted by filtercoffee

Agree. I did not modify my US Section 1. all o2 sensors plugged into the SG headers. secondary o2 is ignored via tune

While I think the Euro cat is denser I can’t seeing it make a huge difference unless it’s the combo of both aftermarket headers and US cat. Resonator or RPi type silencers seems like more effective and practical solution.

What did you do with the Remus?

[filtercoffee]

I have the remus on the car right now, powerloops in storage, I would love to put the powerloops back on and sell the remus... If only I could get the powerloops down to civilized levels...

[eggman51]

Originally Posted by Vanne

pretty sure the Euro section has LESS material in it than the US section, i think you may have got that the wrong way around. on another note, i cant wait to see how your going with your build mate

I think the prevailing logic - and I believe someone did some actual fact finding - is that the Euro cats are higher "cell count" (in quotes cuz I am not sure if that's the right terminology). This is because the US has 2 sets of 200 cell cats, and the Euro configuration has just the one set of 400 cell cats.

I don't know if that makes any measurable difference to sound or performance. Theoretically you would think it to be a little bit less of both.

eg

[filtercoffee]

Thanks for the suggestions! I wonder how custom work ends up being cheaper though. I don't plan to experiment with headers since that's a lot of labor. But the section 1 seems practically free since I have to do a diff service anyway. The euro section 1 should hold its value so I'll only lose on shipping if it doesn't work. I think that's worth a shot before asking a shop to do custom work which I estimate will run me $300-400 in the best case scenario and result in my OEM exhaust parts getting chopped up? I don't quite believe the SGT headers are much louder/more droney than stock euro headers.

[filtercoffee]

SS cans are back on my car. They seem tolerable for now. Full update in this post:
https://www.zpost.com/forums/showpos...4&postcount=16

Thanks for the advice! Appreciate it.