Downpipe vs complete decat..n54 135

[rsgordini]

I believe our cars n54 135i have 2 sets of cats..

One in front of car and one on middle of car..

I have done dowpipes therefore elimaring the front ones..

A bit deeper noise but still very quiet.. very happy with the exhaust sound as is and even happier with the performance gained..

My question is, is it better performance wise to remove middle cats also therefore to be completely decatted or is it not enough of a difference to substatiate the effort and expense?

Im assuming it will be louder too..

 

[Woodies]

I like the sound with no cats and stock rear silencer only. Remove secondary cats with straight pipe and if you still want more sound then play around with silencer. Not massive performance gains, but good sound. Cheaper and easier than DP.


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[Yuben]

Moved to X35 Fanatics

 

[Sendhur]

I believe our cars n54 135i have 2 sets of cats..

One in front of car and one on middle of car..

I have done dowpipes therefore elimaring the front ones..

A bit deeper noise but still very quiet.. very happy with the exhaust sound as is and even happier with the performance gained..

My question is, is it better performance wise to remove middle cats also therefore to be completely decatted or is it not enough of a difference to substatiate the effort and expense?

Im assuming it will be louder too..

Howzit Bud

I have downpipes and decat midpipes, it does make a much better sound and there is no drone, your most power gain will come from downpipes. I dont feel there is much more power coming from the midpipes decat but the sound makes it worth it.

 

[akash]

Agree with the guys.

Its those sound a lot better with the secondary cats removed

 

[Del-Bosc]

Don't the guys normally go with a 1m Mid pipe for better sound

 

[akash]

Don't the guys normally go with a 1m Mid pipe for better sound

I prefer to remove the mid cats and put in a straight pipe.

 

[boost3d]

I have a complete exhaust , downpipe to back box installation done on my n54. As mentioned above, there is little to no performance increase with the mid and rear section but it does have a much deeper tone and sounds really nice with the dct box.

 

[Iceman12596]

I have a complete exhaust , downpipe to back box installation done on my n54. As mentioned above, there is little to no performance increase with the mid and rear section but it does have a much deeper tone and sounds really nice with the dct box.

Any drone in the car ? i think i still have my two cats installed, not sure if i have a resonator.

 

[boost3d]

I have a complete exhaust , downpipe to back box installation done on my n54. As mentioned above, there is little to no performance increase with the mid and rear section but it does have a much deeper tone and sounds really nice with the dct box.

Any drone in the car ? i think i still have my two cats installed, not sure if i have a resonator.

No drone, but my rear seat rattles at exactly 2450-2500 rpm...I am actually fitting new tailpieces and going to fit larger rear boxes next Tuesday, I am hoping the larger boxes get rid of that particular resonate frequency that causes the vibration completely.

 

[NAS325ci]

I just did a back box delete and it's loud and I love it. No performance gains. Stock downpipes and stock mid section cats still there.. some drone but I got used to it.

 

[akash]

Rear box delete is damn loud :cartel:

 

[rsgordini]

So considering that there is no increase in performance or very little.. i won't be removing them..

My clio rs has a full 63mm ss exhaust and is loud so i dont want that on the bmw...

Happy with how it is now..

Thanks for all input guys..