point taken. 3 q's:

1. Would the rest of the exhaust (after cats) be as is ?
2. Do the met cats affect lambda sensor readings - before and after ? (my ECU is already chiptuned)
3. Will met cats affect my yearly exhaust emission inspections ?

 

I suggested to you to don't get a stupid exhaust (only a muffler ?) as SuperSprint. You didn't hear me.


My Mini was for 3 days *without* cat and no lights came on. Maybe the 5 is more sensible. But yes, without kat there is a high possibility 'increased emissions' error come on: cheated lambda sensors exist (they send a right value instead of the real one), but they don't work on all cars.

But the major problem of removing kat is that you'd lose backpressure and your car would go A LOT from 4000 to 7000 rpm but dead under 4k. Exactly as happened on my Mini some days ago.



With a 200 cell, you would pass from Euro4 to Euro3, but here nobody check if you are Euro4 and you have Euro4 emission. I think the limit at the smoke check is Euro1 emission.

 

Are you going to go ahead with this project, NPe ?
For you at least.

Before spending 2k on manifolds, why don't you try to replace cats with 200 cell ones ?
I'm really tempting!
New manifolds would give a better power (than stock) on all revs, but they are pretty expensive comparing to cats, that are cheaper and more power gaining.

 

Yes, I will go forward doing one set for evaluation and reference. (Flanges will be water-jet cut this weekend)
And cats will be replaced at the same time.
I write when design is done.
And hopefully be able to answer questions regard to the upgrade.

If there is any point start producing them? Only time will tell

 

Then you must invite your friend AlexFW to test the 545i and for a spin on your other beasts


Let us know!

 

Work in progress.
15mm stainless flanges
2extra nuts for lambda, to be able to hook up a wideband lambda for measuring the air/fuel mix conditions after the swap.

 

look forward to the next step...