header swap vs. my 'green' side.
 

im thinking about installing an uncatted jdl uel header while keeping the rest of the exhaust stock. excited about the potential for a bit of subie rumble and the pickup in midrange and high end grunt but the eco friendly part of me is curious if the stock cat on the front pipe does any decent job of filtering out exhaust pollutants? don't know if anyone has explored that at all or actually tried to bring their similarly setup car through a sniffer test to see.

Go catless and let your grandchildren deal with the pollution. If you keep all exhaust components stock, will be quiet anyway

Not gonna lie, I have thought about the environmental effects of being catless. Some times I think about putting a catted header on too, but I enjoy the sound and power of a catless header too much.

The biggest part of the pollution will be when you first start the car. At cold startup, you're basically polluting about the same as a car from about 20 years ago before OBD-II.

After cold start you should have same tailpipe as a normal car and should pass tailpipe emissions should it be needed.

-alex

so the secondary cat is effective enough to bring emissions down to legal limits when warm? 👍🏻

Put it this way:

Aftermarket header/OP/FP systems with a high-flow catalytic converter emits less tailpipe than stock. Apex'i and HKS are two companies that offer this setup.

-alex

can you quote any measurement data?

Not without modification. The front cat is the primary and the O2 sensors are positioned to manage it, not the secondary. The secondary cat is likely a two-way catalytic converter, as well, so it would need to be replaced with a three-way to see the same benefit.

But as others have stated, the real problem is the warm-up period. Even if you could move the O2 sensors back and replace the secondary with a three-way, it would still take significantly longer to warm up.

I'm not sure about that. I had JDL catted header and catted front pipe (200 cell cats) and my car failed emissions test here in Aus.

Either install a header the car is dieing for or sell it and hug some trees with a Prius!

If you care about the environment and don't want smell just leave at least 1 cat in the car.

In my 2002 Subaru WRX, we have 3 OEM cats. I removed all 3 and just had 1 200Cel cat in my downpipe.

Had no smell and no issues.

For this car I'd suggest Catted Header + Catless Front Pipe.

Well, if you believe in government subsidies and the mess it creates to grow as much corn... which may still be better than gasoline, mind... try E85 for a greener burn.

And keep your eyes out for an available Tesla roadster.

murica. bikinis. beer. football. powar. giggity.

thanks for the constructive input, those with it. i never knew about 2 vs 3 way cats and i guess just having the stock front pipe is something im comfortable with after the research.

Offset the increased emissions by running E85 :party0030:

Your green side shouldn't be that concerned with removing the cat on your car. Cars aren't the real problem. I'm more concerned about ships, cows, and China. Here's a link to help you realize your cat isn't making a difference.... http://www.industrytap.com/worlds-15...the-world/8182

Living in the city, lots of situations where I want to be quiet and exhaust-smell free.

Also I think the stock exhaust setup on our cars is great, has a well placed resonator, the rear muffler acts as an air diffuser and provides a little extra weight over the rear. And note that it'll sound louder over time as the exhaust ages, the bolts rust out etc. I've noticed that my exhaust sounds much less timid after 70k miles after it's been unbolted a couple times and aged a bit.

Like others said though if you want to clean up emissions then use E85. Some say it almost burns too clean! But also smells like a bar.

I'm completely catless but with the stock catback to keep it quiet. It really only smells in the garage or next to a wall. Rarely do I notice it traffic and friends behind me said they cant smell it.

Now on e85 its almost unnoticeable. The smell is "sweeter" and less noxious.

It used to be said that lawnmowers and power equipment in general polluted more than anything. I would imagine thats improved now that over head valve motors are the norm with those things.

Global emissions, it's a lower portion of the contribution. However, managing vehicle emissions is how the horrible smog issues in various cities is improved; it's still a big deal.

They've found a seaweed to feed cows that does an amazing job managing methane production... it's weird.

I love the power delivery on a good electric vehicle - I won't miss IC engines if they go away.

C

If anyone gives me a hard time about my catless setup, I am just going to point to their big V8 (I don't care if it has cats or not- it guzzles 2-3x the gas my car does), their huge home that needs a LOT more energy to maintain than my apt does. It's all about choices and the holier-than-thou group who folllow all the laws and rules as they are written are the ones raping the environment a lot worse than nay dude in a 4 banger that gets 31 MPG.

As for electric- it still takes power (which in my area is made by burning fossil fuels) and there's line loss to deliver that power to the e-car. I'm not convinced electric is any cleaner than my car is.

As for hybrids- ever car should have regen braking. But there's a prob with hybrids- those batteries are toxic and they require rare earth minerals that often come from countries which use exploited human labor. Clean is a sliding scale...

If this is a common thing, I think a fuel efficient little 2.0L without a cat wont really make a dent.
http://www.lawyersgunsmoneyblog.com/...gd2qzdgjpg.jpg

I see your two smokestacks and raise you smokestacks with skulls!

You're confusing carbon emissions with other pollutants. Removing the cats isn't going to increase your carbon emissions, but it will increase NOx and volatile organics emissions. These are the things that cause smog and acid rain.

Im not confusing it, I know the difference in NOx V.O.C's and CO2. I'm simply trying to say that running your 30mpg efficiently tuned twin without a cat is very small potatoes. Im absolutely not saying cats serve no purpose over all. Not saying I'm ok with everyone removing them either. Just trying to help a guy be less concerned about his choice if he goes catless. The problem is so much bigger than just cars. I'm sick of car enthusiasts being painted as the bad guys. We have man made reservoirs, ships, power plants, factories, agriculture, aviation (do you know how much fuel jets burn?) and major countries that just don't give a shit about the environment.

Hmm. I might not get why gov-t is less active going behind mentioned other biggest polluters, but i'm not getting why logic 'there are others, that pollute more, hence it's ok for me to pollute' should be used to justify either.

Truth, just because they're worse doesn't mean I should. This is why I fully intend on using a high flow cat on my setup.