Emissions options

[LSB.S54]

Hi all first post here and new to the e46 world so appreciate any and all tips. I just picked up my 2001 M3 and it is currently catless, the seller provided the stock headers but one has a rattle so thinking I should install new cats rather than go through the head ache of putting in the the stock ones and that are already on their way out. I am wanting to go the euro route with the cats in section 1 for cost and ease of install, but am only finding high flows 100 cel cats for section 1. I am in colorado where they do a sniffer test and am worried about spending the money on the section 1 system and not passing. Any tips or experience appreciated.

[Tbonem3]

Would you be putting the catless headers back on after the test anyway?

If so, I'd just reinstall the factory headers for the test. Even if they're damaged or old, they'd likely still pass the test (esp if you warm them up well before visiting smog shop).

It's also possible to keep the catless headers installed, and install a catted sect 1 that has bungs to reroute post-cat O2s to in order to pass obd2 (and sniffer) portion of test. I would only buy Supersprint or Fabspeed sect 1 despite their high cost, due to the very high quality HJS cats. Race cats or 100 cell are a waste of your time. This would be the right route to go (if you can afford it) if you want the sound/power benefit of catless headers, but clean up the smell and be able to pass a smog test at the ready.

If the goal is to go back to stock, and leave it that way long term, then you can source a nicer, lower mileage set of factory u.s. headers and be done. Sell your existing catted headers to a scrapper for the value of the precious metals inside, if you want (in the last 2 scenarios I proposed).

[LSB.S54]

Thank you for your reply was planning on going the fabspeed route and keep the catless headers just to keep things easy but was worried since the fabspeed section 1 is still a pair of 100 cell cat I wasn’t sure if it would pass even though it is the higher quality HJS cat. If that doesn’t pass it’s nice to know I can swap in the stock cats for testing and then go back to section 1 cats for daily use to reduce the smell. Comes down to over 3k for a new set of magnaflow CARB headers vs 2k for the fab speed section 1 100 cel sport cats.

[liam821]

Would you be putting the catless headers back on after the test anyway?

Swapping headers every other year sounds like a massive pain in the ass unless you're going to pay somebody to do it...just money I guess. I'm too cheap. haha

[LSB.S54]

Swapping headers every other year sounds like a massive pain in the ass unless you're going to pay somebody to do it...just money I guess. I'm too cheap. haha

We only have to get emission done every two years here in CO but I agree. Hoping I will pass my first go with the Fabspeed section 1 and catless headers and can scrap the stock headers otherwise will keep 'em around to do the bianual swap lol.

[Cronenberged]

Is it 20 or 25 years cars aren't required to do emissions testing.

[LSB.S54]

Is it 20 or 25 years cars aren't required to do emissions testing.

In CO only vehicles made before 1975 and registered as collectors vehicles are exempt from what I’ve read

[Tbonem3]

Thank you for your reply was planning on going the fabspeed route and keep the catless headers just to keep things easy but was worried since the fabspeed section 1 is still a pair of 100 cell cat I wasn’t sure if it would pass even though it is the higher quality HJS cat. If that doesn’t pass it’s nice to know I can swap in the stock cats for testing and then go back to section 1 cats for daily use to reduce the smell. Comes down to over 3k for a new set of magnaflow CARB headers vs 2k for the fab speed section 1 100 cel sport cats.

Magnaflow are junk, don't bother. I thought Fabspeed used same HJS as Supersprint which is 200 cell. All other (not e46 m3) supersprint catted products are 100 cell though - double check with Fabspeed or, since they're the only u.s. HJS distributer I'm aware of, perhaps they can do 200 cell custom for you.

Swapping headers every other year sounds like a massive pain in the ass unless you're going to pay somebody to do it...just money I guess. I'm too cheap. haha

I did a few times, but I love wrenching so...

Now that I have SS HJS, I leave the stepped headers on and just swap the airbox/tune/SAP. Much quicker.

[usdmej]

I am in colorado where they do a sniffer test and am worried about spending the money on the section 1 system and not passing. Any tips or experience appreciated.

years ago when california still required a sniffer test for E46 M3s the euro cats would easily and consistently pass. for any aftermarket 100cell cat the opposite is true. assuming denver's sniffer parameters are the same as california's, you're gonna have to do some sketchy stuff to most aftermarket cats to pass

i know they're harder to come by, but in your case it seems very much worth it to source a set of euro cats. OE quality, high density (clean) and high flowing, bolt it on, enjoy the power gains, and dont think about em again

[ViN]

years ago when california still required a sniffer test for E46 M3s the euro cats would easily and consistently pass. for any aftermarket 100cell cat the opposite is true. assuming denver's sniffer parameters are the same as california's, you're gonna have to do some sketchy stuff to most aftermarket cats to pass

i know they're harder to come by, but in your case it seems very much worth it to source a set of euro cats. OE quality, high density (clean) and high flowing, bolt it on, enjoy the power gains, and dont think about em again

Anyone know where is a good place to source Euro cats? I bought my car with them but I am now getting a code that one of them might be bad and in (NYC) emissions is a genuine pain in the arse.

[bmw m3 s50]

In CO only vehicles made before 1975 and registered as collectors vehicles are exempt from what I’ve read

Why don’t you register your m3 as a collector car and avoid the headaches.

I am so thankful that PA exempts all cars that drive less than 5,000 miles a year.