[DKX4///M]

Originally Posted by CanAutM3

Tuned exhaust length manifolds are critical for efficient scavenging on NA engines. This is not the case on turbocharged engines, first because since the intake is pressurized, there’s no need for exhaust scavenging, second, the turbine of the turbo in the exhaust stream disrupts the pressure waves that would be used for scavenging. So short answer, there’s no performance benefit to equal length exhausts on a turbo engine.

This makes sense. Appreciate response.

[DKX4///M]

Any data on how restrictive the OEM exhaust is?

[LimiX4m40]

Originally Posted by _RS4_

Looking underneath the car I noticed that the exhaust is quite different from the other S58s, you can see a small central resonator (red circle), 2 secondary catalysts/OPFs (blue) and 2 primary catalysts (yellow), but the curve of the tubes and the location of the catalysts it totally different from the X3/4M. I'm surprised to see the primary catalysts so far from the manifolds, any thoughts?

Attachment 2431621


This is the X3/4M exhaust

Knows someone if in EU you can fit the US cat-version on the car? So than you would have an original bmw part without opf 😂 i hope it fits 😁

[acce98]

Originally Posted by LimiX4m40

Knows someone if in EU you can fit the US cat-version on the car? So than you would have an original bmw part without opf 😂 i hope it fits 😁

For sure you can use the US version instead of EU . The main problem ( ( forgetting the cost of O.E. BMW ) is the DME for US same as EU ?

[VIERsr]

Originally Posted by acce98

For sure you can use the US version instead of EU . The main problem ( ( forgetting the cost of O.E. BMW ) is the DME for US same as EU ?

This is the problem.
It's way cheaper an aftermarket exhaust.

[LimiX4m40]

Originally Posted by acce98

For sure you can use the US version instead of EU . The main problem ( ( forgetting the cost of O.E. BMW ) is the DME for US same as EU ?

I think that would not be a problem as you can code everything. The price would be for sure high but at the end you have a original bmw part if you get in a controll (in switzerland they really suck at the moment)

[acce98]

Originally Posted by _RS4_

This is the problem.
It's way cheaper an aftermarket exhaust.

Originally Posted by LimiX4m40

I think that would not be a problem as you can code everything. The price would be for sure high but at the end you have a original bmw part if you get in a controll (in switzerland they really suck at the moment)

You can do everything if you decide to code . Your original question was to add the US version on EU was to be able to have a better sound without modify the DME . To do this it can be mandatory a DME tunes , so , is more cheap an aftermarket exhaust .
Regarding CH rules if you don't overdo it with the noise the will be no problem just keep the rear muffler stock . This what I do with my X4MC

[VIERsr]

If you remove the OPFs you won't match EU/CH emissions rules even if you keep the stock muffler.

[acce98]

Originally Posted by _RS4_

If you remove the OPFs you won't match EU/CH emissions rules even if you keep the stock muffler.

Yes , you are right !
Same CAT - DME Tuning - Lower spring ( If is not omologate ) ecc ecc

Any modification even if approved by the EU / CH rules but not approved by BMW will it could cause you problems( if the car is leased even worse ) so to avoid any legal / warranty issue keep the car on stock .

[V-Eight]

damned OPF.......

Americans, you guys are so lucky!

correction: guys....I don't know if you already knew this....but I've just spoken with one of my friend in Munich (that works in BMW off course) and he told me that also the US spec cars will be equipped with the OPF, as other producers (Ferrari, for example) are already doing.