[sspade]

I know there are few emissions related items up top that are different but Im trying to determine what the differences are in exhaust:

Are the CAT's the exact same?

Is the pipe diameter the exact same?

Is the base muffler the exact same?


I know the N26 has a secondary CAT which Im planning to delete. Im wondering if I remove it... will I have the same, free(er) flowing exhaust that N20's have compared to the slightly more restrictive N26 set up?

[sspade]

I should add:

I know the mounting for the CAT to mid pipe is different between the two engines but Im wondering if the flow rates are essentially the same?

[Jadenkid22]

Originally Posted by sspade

I should add:

I know the mounting for the CAT to mid pipe is different between the two engines but Im wondering if the flow rates are essentially the same?

N20 has less restrictive cat than N26 which means it flows better. The mufflers are the same for both engines but the downpipes are not. You can use a N20 downpipe on a N26 but you would have to weld the rest of your N26 exhaust back on or get a N20 exhaust for your N26.

If you search, theres another post that shows the N26 has like 3 times the restriction of the N20 cat.


Source: MY N26.

[sspade]

Originally Posted by Jadenkid22

N20 has less restrictive cat than N26 which means it flows better. The mufflers are the same for both engines but the downpipes are not. You can use a N20 downpipe on a N26 but you would have to weld the rest of your N26 exhaust back on or get a N20 exhaust for your N26.

If you search, theres another post that shows the N26 has like 3 times the restriction of the N20 cat.


Source: MY N26.

Appreciate the info. Thats what I had feared.

Wondering if removing the secondary CAT is worth the $50 it would cost to have a shop delete it. I know its been done before, just trying to determine if I may pick up a decibel or two sound wise and also know my exhaust is flowing a bit better. I realize there wont be any noticeable performance increase.

Really on the fence about a catless down pipe, mainly for the passing emissions issue.

Also not ready to spring for $500+ muffler yet. That will be the next step.

[Jadenkid22]

Originally Posted by sspade

Appreciate the info. Thats what I had feared.

Wondering if removing the secondary CAT is worth the $50 it would cost to have a shop delete it. I know its been done before, just trying to determine if I may pick up a decibel or two sound wise and also know my exhaust is flowing a bit better. I realize there wont be any noticeable performance increase.

Really on the fence about a catless down pipe, mainly for the passing emissions issue.

Also not ready to spring for $500+ muffler yet. That will be the next step.

Cut that secondary cut ASAP. First mod i did on my car was that, you hear a tiny bit more pops in sport mode, But it definitely frees up exhaust flow. I suggest to also do a muffler delete and get a Injen intake, transforms the car!

[rjd_F30]

So I did a bit of researching on realoem for you and this is what I found.

We already know that the N26 has an extra cat in the midpipe and a more restrictive cat in the downpipe. But the answers to the questions you asked:

Are the cats the exact same: No (see above)

Are the pipe diameters the exact same: Yes. If you look at part numbers, the midpipe and muffler clamp for the N20 is the same part number for the same clamps on the N26, so because they use the same clamps and fasteners, we can assume the pipes are at least effectively the same diameter.

Is the base muffler the exact same: Yes, exact same part numbers for the entire rear muffler assembly on both N20 and N26.

Answers to questions you didn't ask:

Are the pipe bends the same: No. If you look at these two links in separate windows next to each other, you can see that because of the 2nd cat in the N26, the bends in the pipe are slightly different than in the N20. Is the difference enough to make an N20 midpipe not fit on an N26, not sure, but it's worth noting. (https://www.realoem.com/bmw/enUS/sho...diagId=18_0986-------https://www.realoem.com/bmw/enUS/sho...diagId=18_0975)

So all that being said, I think your (and really all N26 guys') best option is to buy a used N20 midpipe for probably dirt cheap, an N20 downpipe and and a good aftermarket muffler. That's what makes the most sense to me anyway.

[jaysal555]

I'm really contemplating a catless dp and AWE resonated midpipe. Are there any N26's out there with that...and stock exhaust as well?

(I think the awe midpipe can attach to the stock exhaust right?)

[sspade]

Appreciate the responses... so far Ive had two reputable shops turn down this job because its "illegal" apparently.

Kinda surprised to be honest. Anyone Sacramento or Bay are know of exhaust shops that will delete a secondary cat?

[BunkerJ]

Originally Posted by jaysal555

I'm really contemplating a catless dp and AWE resonated midpipe. Are there any N26's out there with that...and stock exhaust as well?

(I think the awe midpipe can attach to the stock exhaust right?)

The stock muffler is going to still damper it quite a bit TBH. But yes, the AWE midpipe is made to bolt up to stock components.

[rjd_F30]

Originally Posted by sspade

Appreciate the responses... so far Ive had two reputable shops turn down this job because its "illegal" apparently.

Kinda surprised to be honest. Anyone Sacramento or Bay are know of exhaust shops that will delete a secondary cat?

I was also turned down by one shop for my catless DP... not an uncommon occurrence.

[BunkerJ]

Originally Posted by sspade

Appreciate the responses... so far Ive had two reputable shops turn down this job because its "illegal" apparently.

Kinda surprised to be honest. Anyone Sacramento or Bay are know of exhaust shops that will delete a secondary cat?

1) Go to a car meet or racing event
2) Ask

[N26Ghost]

It would seem logical that the removal of the secondary catalytic converter could negatively impact emissions at the tailpipe, if so, living in CA, won't this cause the car to fail the SULEV standard when getting your smog certification?

This has been my reservation about pursuing a freer flowing exhaust system. The N26 is setup with all of these extra restrictions all in the name of reduced emissions and CA doesn't play when it comes to messing with emissions. Definitely not interested in swapping exhaust systems in and out in order to pass smog every few years.

[MONSTAR]

Originally Posted by N26Ghost

It would seem logical that the removal of the secondary catalytic converter could negatively impact emissions at the tailpipe, if so, living in CA, won't this cause the car to fail the SULEV standard when getting your smog certification?

This has been my reservation about pursuing a freer flowing exhaust system. The N26 is setup with all of these extra restrictions all in the name of reduced emissions and CA doesn't play when it comes to messing with emissions. Definitely not interested in swapping exhaust systems in and out in order to pass smog every few years.

I guess if you went to a certain shop and a few shekels fell out of your pocket and they took your car for a few hours and came back with a pass certification that you would be ok....

[sspade]

Originally Posted by N26Ghost

It would seem logical that the removal of the secondary catalytic converter could negatively impact emissions at the tailpipe, if so, living in CA, won't this cause the car to fail the SULEV standard when getting your smog certification?

This has been my reservation about pursuing a freer flowing exhaust system. The N26 is setup with all of these extra restrictions all in the name of reduced emissions and CA doesn't play when it comes to messing with emissions. Definitely not interested in swapping exhaust systems in and out in order to pass smog every few years.

So I guess an axle back is our only option if we want to stay in compliance?

Was just reading up on smog cert laws in California... as far as I can tell, the earliest a car require a smog test is when it reaches 6 model years old.

[sspade]

Anyone know if there is an O2 sensor behind the secondary cat on N26 that would cause the car to fail smog test if removed?

Only other way they could tell is if a manual probe was inserted at tailpipe. Do they do that in California?

[BunkerJ]

I have a 2013 and I won't have to smog until the 2020 registration year. Plenty of time to enjoy a catless setup (and I have been). It's cheap to have someone swap the part or just do it yourself. The few hours of work each smog cycle is well worth it.

[anotheran]

Originally Posted by sspade

Appreciate the responses... so far Ive had two reputable shops turn down this job because its "illegal" apparently.

Kinda surprised to be honest. Anyone Sacramento or Bay are know of exhaust shops that will delete a secondary cat?

Carb made it illegal for shops to take out the cat for street cars. They’d be fined too

[SFV818]

Originally Posted by BunkerJ

I have a 2013 and I won't have to smog until the 2020 registration year. Plenty of time to enjoy a catless setup (and I have been). It's cheap to have someone swap the part or just do it yourself. The few hours of work each smog cycle is well worth it.

How'd that smog test go for you? I don't have to test until 2022 but want to get the AWE quad exhaust and midpipe for N26 but am worried it will throw a code and/or fail smog. Might just go to a local tuning shop and ask them for a smog rec lol thats gotta be the easiest way unless they think im a narc :/

[sqwinny]

if you do exhaust all the way back behind the cat nothing changes. just sound and a little more power.