New FR-S owner - Trying to understand headers and Tunes
 

I just picked a 2016 FRS with 36k miles. It came with TRD springs, sway bars, and exhaust.

I have seen lots on the power/torque dip in the low to mid range. It seems headers and/or a tune can fix this as well as ad more power. However I am a bit confused after all my searching and need some help.

1)can a tune alone fix the dip or are uel headers needed to do it?

2) I live in a state with emissions. If I run uel headers I know it will remove the cat. Can a header + tune fix the dip, make power and still pass emissions?

3) since I already have the TRD catback, if I added header would it make it considerably louder/drone?

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1. Yes you can run a tune without headers and there will some improvement. With headers and tune there would be a better improvement.
2. Yes you can buy a UEL or EL “Catted” header to retain the 2 catalytic converter setup that the car comes with.
3. Depends. I have a Tomei Expreme EL headers with no Cat and a TRD catback. Its not considerably louder.


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Even if you add aftermarket catted headers it will likely not be legal either, unless they’re compliant with your state’s emission standards. Not sure how many of them out there that are? I was thinking about getting aftermarket catted headers myself, however I spoke to our local road authority and they said they’d have to be engineer approved to be legal where I am. They then pointed me to the link on their website with a list of auto shop engineers that can provide this, I didn’t bother after that. If you want to be 100% sure you’re legal, a cat-back exhaust is OK. It is changing or removing the cats that is the issue. You can always roll the dice and you might not get caught etc. Bureaucracy. :barf:

1) disclaimer, no personal experience on this, but from my research a tune will help with the dip, headers not needed. Tune + header's seems to be the common denominator in removing it almost entirely.



2)There are UEL header's out there with converters. Important note here is that removing any catalytic converters is an illegal modification, regardless of what state you live in, as the removal of emission control systems is prohibited by the Feds. I'm not sure if Colorado is a state that runs California style laws, where you'd need CARB certified catalytic converters.


There's basically two emission standards in the US: California and Federal. The majority of states have adopted to the Federal standard. I know a few states, other than California, have adopted their standards (CARB). Not sure if Colorado has or not.




3) Depends on the header. I'd recommend some dedicated youtube time searching various exhaust setups and how they sound. There's quite a few videos there for these cars. Even better if you can find other owners and personally listen to their setups.



Overall, yes, you will be louder. The amount of increase, and whether you'll run into drone issues, is dependent on the design of the header.

1- Tune alone can improve yes, Header/Tune is best. There are dynos on here that show the torque curve vs stock so you can see for yourself.

2- "Pass" emissions and be "legal" are 2 different things. I live in a state that just hooks up OBD and I have been passing with a catless setup because my Check Engine Light (CEL) is not on. The Tune with OFT and I assume with Ecutek also, will fool the ECU and keep CEL off..
Or the dlrs I've done the state inspection at just don't care to do a visual under the car, because there is clearly no cat underneath. (I will be going to a catted front pipe again soon though).
I have lived in other states that also just hook up the OBD and check for lights.
However I've lived in other states that hook up OBD, do a visual underneath with a mirror, and run a tailpipe test. So I'm not sure how they actually check in Colorado.
You could wait until your next inspection and take note of how they inspect your car, before getting the header.
As far as the tune, you can always flash back to stock and then back to the tune, so no harm there.

3-it will be louder with a catless header, yes. How much you're comfortable with is subjective.


Colorado is not a CARB state.

CARB states.
Connecticut, Delaware, Maine , Maryland,Massachusetts, New Jersey ,New York, Oregon , Pennsylvania, Rhode Island , Vermont , Washington

But being a CARB state first and foremost means for warranty purposes.
I am not sure that being a CARB-state means that people purchasing aftermarket parts, say an intake or supercharger, have to be "CARB-certified" with the sticker and everything like it does in California. Other than the converter itself, which I assume should be compliant. Maybe someone in one of those states can chime in.

BTW nowawdays, the OEM parts that come on the car on Cali-market vehicles are the same exact part as Federal.
In the past there were 2 different Cats, one for Cali vehicles and one for Federal vehicles.

I just picked up an OFT tune and am running stage 1 with just a catback and the torque dip is definitely improved but not completely gone. I don't think I'm going bother with headers for emissions purposes but I'm probably going to toy around with running e85 once the weather gets a little warmer which you can do with just a tune also.

I run oft stage1 and the torque dip is still there. I just drive around it, and it adds 'character' to the engine IMO (like crickets lol). If you do decide to change things up, and are considering an oft, I recommend just getting the oft first, then upgrading the header. If you decide to go ecutek, you might want to consider doing both at once, as I believe you pay for each tune individually.

If you want a header, I highly recommend a tune to go with it. You might be making your car slower and less healthy otherwise.

CONGRATULATIONS!

Your car has everything you need for average driving - :)

Like ol @Spuds said (in one of his more lucid moments) , just "drive around" the perceived "torque dip". Hell, if you hadn't read about it on this forum, you wouldn't have ever noticed the so called "torque dip". It would have been just the way the car runs.

See there, just leave the engine alone, no fuss, no mess, no expense, no emission worries.

Just don't be caught below 3,000 rpms when you head into this curve going up this hill with a Mustang on your tail end - :thumbsup:


humfrz

FTFY :P

Yep, that's more better - ;)


humfrz

Drive it for a while and make up your own mind as to what it "needs". From reading this forum and many other sources I was quite convinced I needed at least a super charger. Then after actually driving the car I found I didn't need a thing. The dip was meaningless for daily driving and since I wasn't taking on Mustangs from stop light to stop light I had plenty of power.

I barely notice the torque dip. I'm not doing hard pulls against Mustangs from stop light to stop light.

The advice you get here regarding legality in Colorado is going to be all over the place, because most of us are not in Colorado and have no idea how strict they are there. You might try posting that question in the Rocky Mountains forum instead. I'm not sure how active that group is.

I would also suggest dropping by a speed shop or tuner shop in your state and asking them. They should know where the line is. You might have to "talk around" the subject to get an answer, since a shop isn't going to want to get caught advising people to break the law even if there's no enforcement mechanism to catch you.