[SlumpLord3000]

Hi,

I have a 335i N55 F30 and I'm looking to install a catted downpipe.

active autowerke downpipe n55 that throws no CEL is 1.2k(300 cell). I was thinking of running 200 cell cat like Turner Motorsport High Flow Catted Downpipe - N55 with an L shaped O2 spacer so it doesn't throw a CEL.

https://www.ipdusa.com/products/1209...cer-IPD-125604

I'm wondering if anyone is running a similar DP and if the smell is noticable?

Any recommendations are welcome.

Thanks

[thejeremyman9]

Been discussed in detail many times. A spacer may or may not temporarily prevent the CEL and/or get the emission monitor ready. It's not really a long term solution, and it shouldnt be, per MHD you shouldnt run any kind of spacer or anything, even on the secondary O2 (although this is somewhat debated).

If you dont need the get the monitor ready, you can get a cheap catted DP and code out the CEL. If you need the monitor ready, get a good DP, or swap to OEM for emissions inspections.

[mike@x-ph.com]

Active Autowerke downpipes are guaranteed not to trigger the check engine light; if yours is, I recommend contacting active autowerke for a replacement.

[yupetc]

I have over-bought a bunch of spacers, elbows, extensions, ones with a built-in cats; and I can tell you that you may find that combination which will seemingly work at one setup, but with these BMW's I've always ended up with a code after a few hundred miles. The most common error code I get is something along the lines of "delay in bank 2 reading" or something like that. And if I were to make suggestions for anyone out there, I'll say save yourself the effort and just get a tune or stay with the catted DP that guarantees no CEL. Or you can always just use the stock DP.

[SlumpLord3000]

Originally Posted by yupetc

I have over-bought a bunch of spacers, elbows, extensions, ones with a built-in cats; and I can tell you that you may find that combination which will seemingly work at one setup, but with these BMW's I've always ended up with a code after a few hundred miles. The most common error code I get is something along the lines of "delay in bank 2 reading" or something like that. And if I were to make suggestions for anyone out there, I'll say save yourself the effort and just get a tune or stay with the catted DP that guarantees no CEL. Or you can always just use the stock DP.

Thank you for the reply. I am concerned about the smell but also 200 cell would allow more airflow than 300 cell. Since I down own a garage and I have to pay for removal of DP it usually cost $300 per job and pay again for the swap.

Any difference in smell in 200 cell vs 300 cell? Also any noticable difference in turbo spool and or power?

Thank you all for contributing your knowledge.

[BRK]

Went through this with a ford turbo 6 in Australia.
200 cell will produce very little odour. The software turned off the number 2 oxygen sensor. Car made 400 whp through that cat and it ran flawlessly. I have no data on flow rates through 300 cell versus 200 cell and I would suggest that the od of the actual cat will also contribute to flow restriction.

[yupetc]

Originally Posted by BRK

Went through this with a ford turbo 6 in Australia.
200 cell will produce very little odour. The software turned off the number 2 oxygen sensor. Car made 400 whp through that cat and it ran flawlessly. I have no data on flow rates through 300 cell versus 200 cell and I would suggest that the od of the actual cat will also contribute to flow restriction.

Yes, absolutely agreed with the quoted comment. You can run a 200 cell with a narrow OD and it cannot outflow a 400 cell cat that has a much larger OD.

Henceforth, some DP makers can configure 400 cell in their cats with enlarged effective OD and achieve higher flow while maintaining a emission test passage. This to me is much more brilliant to do than finding the right O2 adapters and trinkets. However, it will come down to how much money will you spend to suit your need. Those enlarged 400-cell cats won't come cheap.

[thejeremyman9]

Originally Posted by SlumpLord3000

Thank you for the reply. I am concerned about the smell but also 200 cell would allow more airflow than 300 cell. Since I down own a garage and I have to pay for removal of DP it usually cost $300 per job and pay again for the swap.

Any difference in smell in 200 cell vs 300 cell? Also any noticable difference in turbo spool and or power?

Thank you all for contributing your knowledge.

+1 to both comments above, you cannot conclude cat flow based on density. There's not guarantee a 200 will flow better. The fabspeed has a huge diameter at the cat to increase cross sectional area and flow for that exact reason. Also the actual honeycomb design of the catalyst will make a difference. Too many variables to generalize.

I believe Eidos is still running fabspeed as are other people making well over 500whp. You won't notice any difference between something like fabspeed and AA.

[SlumpLord3000]

Thank you everyone for contributing. I have placed an order for AA catted DP.

[mike@x-ph.com]

Originally Posted by SlumpLord3000

Thank you everyone for contributing. I have placed an order for AA catted DP.

Congrats