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jamesmcd

Catless downpipes for 335i

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Mine is completely stock without a tune and it pops and bangs. 
Do the e92’s have a different exhaust than the 90’s/91’s?

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On 10/19/2019 at 9:53 AM, AlexL said:

How do you not have no pops and bangs? My car is standard exaust and tune and it pops and bangs on decel and sometimes on upshift

It just gave a deeper sound without adjusting burple on the tune. It was a 135i so maybe different exhaust system. 

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23 hours ago, str8_6 said:

Mine is completely stock without a tune and it pops and bangs. 
Do the e92’s have a different exhaust than the 90’s/91’s?

I seem to recall something about the E90/91 having an extra muffler?

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On 10/20/2019 at 1:17 PM, str8_6 said:

Mine is completely stock without a tune and it pops and bangs. 
Do the e92’s have a different exhaust than the 90’s/91’s?

Yes, they don't have secondary cats so are a bit louder. 

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Hi anyone get more vibration after fitting catless downpipes? Mine is vibrating more than before kind of loose confort. It’s normal???

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On 12/2/2020 at 11:35 PM, Seba said:

Hi anyone get more vibration after fitting catless downpipes? Mine is vibrating more than before kind of loose confort. It’s normal???

Not that I remember. However I put some bellows in.

 

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On 12/2/2020 at 11:35 PM, Seba said:

Hi anyone get more vibration after fitting catless downpipes? Mine is vibrating more than before kind of loose confort. It’s normal???

I'm going with an increase in vibration that makes the car less pleasant to drive ? If so, then there are a number of factors at play that could result in an increase in vibration compared to stock catted pipes. The catless pipes may be made from a lighter gauge of material than OEM pipes if they are of the lower cost Chinese variety. Lighter material is less able to attenuate/contain the pressure waves generated by combustion. The cats in the OEM pipes reduce turbulence in the exhaust flow and dampen pressure waves, which help keep the exhaust quiet. What you have installed are effectively two resonators without any internal baffling or sound absorbing material, and if you are unlucky you may get an annoying resonance at certain engine speeds.

In addition (as mentioned above) you have eliminated the flexible bellows section from the exhaust system. This will allow lower frequency vibration from the engine to transmit to the exhaust system that is rigidly bolted to the chassis under the drivers seat. So it is possible that this vibration may be felt inside the car. Generally speaking I would expect all of the above to produce "vibration" that more obvious at certain engine/road speeds rather than being constant at all speeds. Otherwise there are the usual suspects of the pipes rubbing against each other or the frame or loose fasteners.  Good luck :)

Cheers...

PS: For what it's worth, if I ever decided to go to the trouble of installing downpipes I would get the Wagner pipes. No sense in expanding to 3 inch and then squeezing back down to 2.5 inch. Gives a bit more clearance for installation as well.

wagner_bmw_n54_135i_335i_1M_catless_downpipe_e82_e88_e90_e92_e93_e91-2__14999.1574095903.jpg

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