[sparky_phantom]

I found a diagram of the N55 exhaust system and it looks like has one down pipe and branches off to two pipes. Then it appears it connects to a center silencer and then back to two pipes to the rear mufflers. My question is, can you remove that center silencer and would it help with sound? I plan to get a down pipe in the coming months to take off my cat. I have already done the golf mod.

[Johnny Boost]

Can you post a picture of the "silencer?"

[sparky_phantom]

Originally Posted by Johnny Boost

Can you post a picture of the "silencer?"

It is toward the end of the pdf.

Link

Trying to upload picture, but it is asking for a link.

[SMH]

Could it be a resonator? If you remove that it'll be louder.

[sparky_phantom]

Originally Posted by SMH

Could it be a resonator? If you remove that it'll be louder.

Could be, I honestly don't know much about the N55 exhaust at all.

[Manberg]

Its just an X pipe so the sides of your exhaust can briefly talk to each other which helps with scavenging. As far as sound goes I don't think it does anything.

[sparky_phantom]

Originally Posted by Manberg

Its just an X pipe so the sides of your exhaust can briefly talk to each other which helps with scavenging. As far as sound goes I don't think it does anything.

Do you know if it helps or hurts performance if removed and just made into two separate pipes down?

[Joey911]

Originally Posted by sparky_phantom

Do you know if it helps or hurts performance if removed and just made into two separate pipes down?

Hurts. Pressure on both side cannot be equalized.

Just opinion.

[JETmn]

Originally Posted by Joey911

Hurts. Pressure on both side cannot be equalized.

Just opinion.

I think you read his questions wrong. An X-pipe (correctly done, which we can assume the OEM one is) will help performance and also make the car sound much better. The Xi's do have cats in the mid pipes, but RWD cars do not. You won't gain anything by removing the X-pipe. The exhaust on the 335 is actually very well done and not a large restriction (except the cat in the DP obviously). If you haven't done the DP yet, do that. It makes it sound nicer and is a nice bump in power.

[Joey911]

Originally Posted by JETmn

I think you read his questions wrong. An X-pipe (correctly done, which we can assume the OEM one is) will help performance and also make the car sound much better. The Xi's do have cats in the mid pipes, but RWD cars do not. You won't gain anything by removing the X-pipe. The exhaust on the 335 is actually very well done and not a large restriction (except the cat in the DP obviously). If you haven't done the DP yet, do that. It makes it sound nicer and is a nice bump in power.

He's talking about removing the xpipe..

[hz_diesel]

Originally Posted by Joey911

He's talking about removing the xpipe..

He is def talking about removing the secondary cats. It sounds like he mistook it for a resonator or silencer. He said the center too, the x-pipe is more towards the rear Joey.

If you are indeed talking about the secondary cat then you can delete it, it doesn't add much volume but makes it a bit more raspy if you have a deep toned exhaust.

[Joey911]

Originally Posted by hz_diesel

He is def talking about removing the secondary cats. It sounds like he mistook it for a resonator or silencer. He said the center too, the x-pipe is more towards the rear Joey.

If you are indeed talking about the secondary cat then you can delete it, it doesn't add much volume but makes it a bit more raspy if you have a deep toned exhaust.

OP asks can he remove center silencer.. I assume he's referring to the Midpipe - X-pipe.

Secondary cats are already "separated" pipes, and OP asked if he can make the X-pipe two "separate" pipes..............

[sparky_phantom]

Not the second cats. Mine is a RWD and from what I can tell I don't have secondary cats.

[EB89]

Originally Posted by sparky_phantom

Not the second cats. Mine is a RWD and from what I can tell I don't have secondary cats.

I don't see why you would remove it, ive never heard of anyone doing it, I doubt it restricts any power.

[sparky_phantom]

Originally Posted by EB89

I don't see why you would remove it, ive never heard of anyone doing it, I doubt it restricts any power.

More just curious on it.

[EB89]

Originally Posted by sparky_phantom

More just curious on it.

Fair enough

[f87.lci]

I know this topic has been beaten to death but I still would like to get a bit more clarity . Most of the videos I have seen involved N54 or N55 coupes.

I have a 2011 335xi (N55 ) sedan currently with BMW Performance exhaust and Eurocharged tune. I am thinking of getting a catless DP to make the most out of the tune and need some help/advice.

I want to know from someone who has this setup, how loud/raspy it will be. Will it drone at all on the highway? I have been told that on our n55 sedans we have a secondary cat in midpipe as well as a factory resonator so it should be okay. Does it make sense to replace the factory resonator with 1790 Vibrant resonators or that is more or less for people that have coupes that do not have a factory resonator in place. I currently like how my car sounds and don't want it to loose that BMW refinement.

Can anyone with E90 n55 sedan pls comment if you have this setup. I need some help/advice deciding if I should go ahead with the catless dp or leave it as is.

Thanks guys!