Header info for a newbie
 

So I'm interested in getting an aftermarket header for my frs but I have a few questions.

My first concern is that when I look up headers for my frs they say that they are for off-road use only. Why is this? Will I risk the chance of getting pulled over and ticketed because of an aftermarket header?

Also, are there any concerns with the reliability of aftermarket headers? Will I have to worry about anything breaking down?

I'd ultimately like to get a header and an open flash tablet to increase my horsepower. Are there any other problems that could come with installing an aftermarket header? Thanks!

The primary catalytic converter for our car is in the header. Federal regulations prevent any alterations to the factory emissions control system, of which the catalytic converter is a part of.

To that end, any aftermarket header can only be sold for off-road use.

Will you get pulled over for it? Probably not. Will you fail a state emissions inspection? Possible. Depends on your state and testing facility, as well as luck of the draw sometimes.

Reliability - it's not a moving part, so the worst that could happen is you have an exhaust leak somewhere. Either an ill-fitting flange, or a crack in a weld, for example. Won't stop your car from operating, but could lead to additional noise, as well as exhaust/heat escaping from a part of your exhaust system it's not supposed to.

I believe it says "for off road use only" for headers that are catless, therefor making your vehicle unable to pass an emissions test. The car comes stock with two and altering it down to one effects the final product coming out the exhaust tips. It is most likely there because the item was designed for track use and the company does not want to get sued. This is my theory anyways, hopefully someone can back me up.

There should be no reliability issues with an aftermarket header if you buy from a reputable brand. I would strongly recommend digging through the forum for user reviews and dynos. If longevity is a concern of yours, you can a ceramic coating for the header.

I will be in the same market as you shortly. Headers and OFT once I move to my new house and rent goes down substantially.

Have you considered the OFT and the OFH together? I am consider the OFH, the JDL, or the Nameless. Havent made up my mind yet :iono:

Damn, @Foobar beat me to the punch :bonk:

Yeah that's exactly what I'm considering. I think an increase of roughly 20hp is pretty decent for around $1000. I just don't want to do it if it were to cause problems down the road. I also don't like noises that aren't supposed to be there. I'm rather OCD about random noises...

I would be scared of a cheap catted headers cat clogging and fucking everything personally..

I am the same way. I pulled off the highway about a week ago to fix the stupid rattle from rear deck.

Your exhaust will sounds bit louder I would imagine. Are you planning on any other exhaust mods?

Agree. I didn't mention problems with aftermarket cats as most of these aftermarket headers are probably cat less.

Chances of you getting pulled over with a catless system is extremely unlikely unless you're driving like an asshole and your car sounds like a Harley. Generally speaking, you won't get pulled over.
Again like a member said above, companies use the "for - off road use" because it's federally illegal to sell exhaust components without cats for the street. Plus companies can get sued if they forget to put the "for off road use only" if they're selling an aftermarket exhaust component.
Yes, get the OFT + your header of choice (anything but Borla and cheap brands). You'll love it!

Yeah I'm thinking about a cat back exhaust


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As far as emissions go for catless headers, if all they do for emissions testing is plug into your OBDII port and pull data will they be able to tell you've changed out the header? Anyone live in an emission-testing zone and having issues? My county doesn't do emissions testing, but it's always possible that I'll move to a county that does. I know some vehicles require an O2 sensor replacement to "trick" the ECU so you don't throw any codes with a catless header, but haven't seen anything about this for the BRZ.

I am also interested in what happens once I need to get an emmissions test. Is there an easy way to pass it with an ofh is installed?

You can place the o2 sensors around the secondary cat when the primary cat is removed with the stock header. From what I've been told this is enough to make the ecu think the primary cat is still there.

So you will need an o2 sensor bung with cap and an o2 extension wire. You have the bung welded into your front pipe after the secondary cat and place your after-cat sensor there. Your before cat sensor goes where you would normally put the after cat sensor. You plug up where you would normally put the before cat sensor.

I installed my catless uel header this past weekend and have yet to throw a cel. I will be doing this sensor relocation this weekend.

I would avoid this...mainly because this car already is extremely picky ecu-wise when it comes to mods that affect a/f ratio i.e header/intake. There is no definite cure to CEL without a tune just yet...and a tune=no warranty work.

So basically what the OFT does is tune the ECU so you don't throw any codes? Are all dealers going to go into your ECU to see if you've installed a tune? Since the OFT is a tune and not a piggyback, there's no physical evidence that you've tuned it. They'd have to pull the ECU data to see it from my understanding.

Generally any tune for catless headers will adjust AFR ignition timing valve timing ect for best horsepower from headers and it will also disable the CEL code for Cat Efficiency which is the one you get when removing cat.

With OFT you can flash back to stock but you will probably then get the CEL fro catless headers, the service guys are going to notice the headers anyway so little point in flashing back to stock.


If no tune use O2 sensor spacer on second O2 sensor. The first O2 sensor is used for AFR sensing for engine so its not effected (ie one before the CAT in header.

The 02 sensor spacers are put on the secondary O2 sensor to "fool" it to thinking the cat is still their, sometimes you will still get the odd CEL thrown.

Yeah, no.

The thing is once you have something like Engine Failure they are going to do is look into it deeply to place blame on you. So they'll check the ECU to see if it's been flashed at all. That and they'll probably look if there is any documentation of mods when you bring it in for service that the dealership noticed if they decided to do that... This is the only reason i refuse to tune this car because i want to enjoy having a warranty just in case some shit happens... after warranty runs out:burnrubber:

Your response is very descriptive thanks

@EpicNameBro : How different is the secondary cat in terms of functionality? I'm guessing relocating the sensors around the secondary is better than having both sensors reading exhaust gas coming straight from the engine, no? I'd prefer to wait until warranty expires before tuning.

I've been running my uel header for a full tank of gas now and I've had slightly better mpg with no cel yet.

They reduce emissions during the start up phase before the primary gets to temperature... So with that being said the secondary cat has no role whatsoever in O2 sensor function or emission control feedback function. The primary determines if the car is running too lean or rich and adjust as such. Going off the second cat gives a false reading which depending on your set up may be doing more harm than good...

From what I read, it does assist in catalyzing pollutants while the primary heats up. Once the primary is fully functional, the secondary has little to do with pollutants since the primary already had it's pass at the gas (pass gas lol).

My thought is that the secondary is still a catalytic converter, as long as it is converting/catalyzing within the acceptable threshold, it should be fine--aside from cold start emissions. I will continue to look for more info on this.

If you can point me to some reading on this I'd appreciate it. I read your first line on a BMW board.

This kinda makes me reconsider getting an openflash header... Is it really confusing as all that sounds or is there a simple solution?

There are simple solutions, but there are trade offs.

If you have emissions testing, You can do some research and try what some of these people have said, or just switch back to your stock catted header/stock tune every year or two. Will cost you $20 in gaskets, and a few hours in labor.

If you have a serious failure, and take the car in for warranty work, you may be screwed out of the warranty coverage because they can blame just about any mechanical failure on a tune, regardless of it's actual impact. In most cases if you are curtious and persistant you will still get covered, but this is just something you have to consider.

kind of makes me long for the old days when you didn't have to tune the car to accept a new air filter.

my ofh is scheduled to get here Thrusday, because we don't have emissions testing here.

I'm thinking of having a shop make me a new front pipe with a cat and place bungs before and after it for o2 sensors.

I really want to know the technical differences between the primary and secondary cats tho. If they are close to the same thing Idk if it's worth going through the hassle of getting a replacement primary.

If you had to replace the secondary cat, do exhaust shops sell 'secondary' cats or are they just slapping on a universal?

The primary cat people are referring to the one in the header. The secondary cat refers to the one in the front pipe.

....I know it's in the header. I have an aftermarket header and thinking about having a new primary cat installed elsewhere.

The secondary is mainly there to clear up whatever the primary didn't get in terms of breaking down gases etc. It's not there to monitor anything it just acts as a second filter once the car is warmed up. Essentially creating a fail safe for a car to meet the strict emission laws...

Yes, that is understood. But I wonder what differentiates a secondary cat from a primary cat technically/internally? Is it different catalysts? Less catalysts?

If you call an exhaust shop to replace a secondary cat due to failure or whatever, do they just slap on a universal regular cat in its place, or do they have special cats used only in the secondary position?

My goal in this is to determine a functional fix to losing the primary cat that was in the factory header. My possible solutions are:

1. Use the oem secondary cat as the primary, relocating the o2 sensors before and after it.
2. Have the oem secondary cat replaced with a 'primary' cat at an exhaust shop, and have the o2 sensors relocated before and after it.

This question might be best answered by a shop that specializes in exhaust systems (performance shop, not Meineke\Midas etc).

If you damage your cat, the shop would usually replace it with OEM equipment, as that's what federal regs call for.

If its an aftermarket piece, you're on your own, they won't touch it.

There's no real functional difference between primary and secondary. Primary is monitored by the ECU, secondary is just a redundant backup. Technically, both are required by federal regulations to remain OEM and intact for the life of the warranty which is 8 years or 80k miles as they are part of the emissions control system.

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I'm mainly trying to a) Not have a CEL and b) Not mess up my car by my ECU trying to correct the air\fuel ratio based on the o2 readings. Maybe I can have the shop cut the factory cat out of my header and put it in my front-pipe? Just kidding (kind of) but I really want to figure this out.

I'm not sure what you're trying to avoid - you're going to want to get a tune for the header anyway to maximize the benefit so that should address the ECU and CEL for you.

Are you trying to get by without a tune? If so, you'll need some kind of defouler setup to trick the o2 sensor and avoid CEL. That's a lot less involved than trying to move a cat and sensors around to another part of the exhaust system.

I told you what I'm trying to avoid in my previous post. Another member moved his sensors around the secondary and has no cel for 5000+ miles. My only concern is the ecu messing with a/f ratio

And I'm telling you that a proper tune will handle what you need, so are you tuned or not?

No tune and no plans to at least until warranty is expired... it just isn't with it to me to spend $500+ on 10hp. The cel can be fixed other ways, and hopefully this ecu correction that I read about on the forums Idk how legit it is

Then yes, in that case you want to move your sensor setup to use the secondary, or take a chance on a defouler which isn't always foolproof.

Sorry for not getting a clear understanding of your situation. Preferably get a tune, next easiest path is defouler, last resort, move the sensor setup to use the secondary and hope the secondary is enough to meet the ECU threshold for keeping CEL in check.

I don't have experience with that so I'm afraid I can't really add more to this.

I'm guessing the secondary is better than using a mini-cat or o2 extender piece. Is that what you mean by defouler?

And as I said, another member has been using the secondary for a while with success

Or you could avoid all these problems and get the P&L catted header (or the one by FT86-speedfactory). It makes power, it isn't loud so you won't get pulled over, it won't throw any CELs - even without a tune, and you will pass your e-test. WIN-WIN-WIN. Combine that with the openflash tablet and you're golden.
:party0030:

Open FLash Tablet with Open Flash header for a Grand, awesome deal. You get the part and it does more than make sound. And I believe you will see closer to 20 hps with Shivs Tune

A grand for a header, no thanks. And I heard people were still getting cel's with the ft86speedfactory header.

no, a grand for a header and a tuning tablet/data logger + tunes

also, If you wouldn't spend $500 for 10hp, then why bother with a header? A header without a tune will cost more than $500, and will not net you more than about 10hp n/a