Aftermarket Header Finishes

[dukeofchen]

Disclaimer that I don't remember squat about metals and surface treatments from my MechE degree.

But given we have plenty of people cruising through smog with Euro cats + headers, it would seem that a major impediment to running non-OE headers with euro cats is the stainless finish being a visual red flag.

So I'm wondering, as blasphemous as it would be for a set of beautiful headers, is it possible to obtain an OE-like surface finish on an aftermarket set of headers through some process? Or does it fundamentally come down to a difference in the materials used?

[Slideways]

There should be a dark grey or black thermal coating similar to Swaintech white lightening coating. Maybe Swaintech have something other than white.

Jet Hot is another brand that used to be popular.

Redish in the UK use Zircotec -

[Altaran]

I used Cerakote C-186-P on mine. It's a dark olive color, but they have grey and black available as well.
Probably a dark gray will be the most inconspicuous...

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[dukeofchen]

There should be a dark grey or black thermal coating similar to Swaintech white lightening coating. Maybe Swaintech have something other than white.

Jet Hot is another brand that used to be popular.

Redish in the UK use Zircotec -

Awesome, great info. Looks like among these companies Jet Hot might have a passable match off the shelf, at least based on website pictures.

I figure anything dull grey-ish would pass the smell test since most smog guys don't bother poking around trying to see behind the heat shields.

[Sharocks]

I had coated headers in the past and TBH, it does nothing other than something to look good kinda.

If you stare at your headers often (weird) then by all means but there haven't been a lot of proven positives for doing so.

[digger]

you aint gonna fool anyone.

[dukeofchen]

I had coated headers in the past and TBH, it does nothing other than something to look good kinda.

If you stare at your headers often (weird) then by all means but there haven't been a lot of proven positives for doing so.

Per my original post, I don't care about the aesthetics or performance benefit, I was thinking along the lines of not attracting attention when getting smogged.

you aint gonna fool anyone.

Eh, I wouldn't take that as a certainty if the color / finish is close enough so as not stand out too much among the range of makes and models these guys come across, it's not as if they'd have a photographic memory of the factory finish on an OE E46 M3 header.

The majority of smog guys I've been to don't bother jamming their heads into the engine bay trying to see around the heat shields, or take more than a second with an inspection mirror underneath to get a look, if they even bother at all. The idea would be to pair them with euro cats which are OE stamped parts. And plenty of members here are flying through with euro cats, if anything you're just as likely to get questions about stock headers because they don't know where the cats are located and can't get a clean look at them.

[AWE46M3]

Per my original post, I don't care about the aesthetics or performance benefit, I was thinking along the lines of not attracting attention when getting smogged.

There’s a heat shield that covers the headers, completely hiding them from view during a visual inspection under the hood. However, if the shop puts your car on a lift to inspect the catalytic converter setup, you’ll likely fail—even if you have Euro cats—because U.S. headers have the cats built into them. And if the shop is picky enough to put you on a lift, they will likely be aware of this detail.

[elrichmeister]

There’s a heat shield that covers the headers, completely hiding them from view during a visual inspection under the hood. However, if the shop puts your car on a lift to inspect the catalytic converter setup, you’ll likely fail—even if you have Euro cats—because U.S. headers have the cats built into them. And if the shop is picky enough to put you on a lift, they will likely be aware of this detail.

The place i went to took forever looking for cats, they only had a mirror with stick was inspecting thoroughly. He was questioning section 1 of exhaust since it had only 1 resonator, maybe he thought i removed 1 cat which would be weird, i had to tell him the cats were on the exhaust manifolds.
If i ever do euro conversion ill have to find a new smog shop lol.

[dukeofchen]

There’s a heat shield that covers the headers, completely hiding them from view during a visual inspection under the hood. However, if the shop puts your car on a lift to inspect the catalytic converter setup, you’ll likely fail—even if you have Euro cats—because U.S. headers have the cats built into them. And if the shop is picky enough to put you on a lift, they will likely be aware of this detail.

Most of the guys at my local smog shops seem pretty lazy, and I don't think some of the ones I've been to are even equipped with a lift. Probably helps that I don't at all fit the profile of a potential narc 😅

I concluded a while ago that the hassle of aftermarket exhausts isn't worth the squeeze for me under the CA regime, with the amount of work it'd take to swap them back to stock every 2 years to guarantee a pass. But as someone who does care about the emissions I'm contributing on a broader scale, it's annoying that a set of lower mileage euro cats might still get failed even though my stockers pushing 200k are probably toast at this point.

But every so often, I get that itch...hence being interested in the art of the possible.

[dukeofchen]

The place i went to took forever looking for cats, they only had a mirror with stick was inspecting thoroughly. He was questioning section 1 of exhaust since it had only 1 resonator, maybe he thought i removed 1 cat which would be weird, i had to tell him the cats were on the exhaust manifolds.
If i ever do euro conversion ill have to find a new smog shop lol.

Yep this is similar to my experiences, the one time a guy seemed sketched out I think what aroused his suspicion was my rasp terminator section 1, which I guess could be a grey area depending on your reading of the regs. That was when I thought that an OE euro cat might have been less suspicious, he took his sweet time because I was the only one there at that time.

[digger]

Per my original post, I don't care about the aesthetics or performance benefit, I was thinking along the lines of not attracting attention when getting smogged.




Eh, I wouldn't take that as a certainty if the color / finish is close enough so as not stand out too much among the range of makes and models these guys come across, it's not as if they'd have a photographic memory of the factory finish on an OE E46 M3 header.

The majority of smog guys I've been to don't bother jamming their heads into the engine bay trying to see around the heat shields, or take more than a second with an inspection mirror underneath to get a look, if they even bother at all. The idea would be to pair them with euro cats which are OE stamped parts. And plenty of members here are flying through with euro cats, if anything you're just as likely to get questions about stock headers because they don't know where the cats are located and can't get a clean look at them.

arent they looking for the catted header? paint wont change that plus i have yet to see an aftermarket exhaust that is constructed the same way OEM do

[dukeofchen]

arent they looking for the catted header? paint wont change that plus i have yet to see an aftermarket exhaust that is constructed the same way OEM do

I don't have enough data points to say it's the norm, but there are plenty of anecdotes on here that suggest a lot of smog guys don't check their diagrams for the precise stock location of the cats before taking a peek. I could be wrong and maybe they have that info in their computers when they pull up the VIN, in which case it comes down to luck if they neglect to look at it. Euro cats looking OE, because they are OE, seem to pass the smell test for these guys despite being in section 1 rather than the headers.

Hence my curiosity about pairing them with an inconspicuous aftermarket header – although at that point one might as well go euro headers (if obtainable) to complete the look unless you're determined to run supersprints.