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Hey does anyone know anythign about this? Does it work as described? Does anyone have this in their car or something similar that they thought works well? What effect do these have on MPG, Idle etc?

http://www.ebay.com/itm/HONDA-Intake...item3cbd480282

Im looking to see if these 01 civics have any cheap mods that increase acceleration, and dont hurt the engine.

 
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Its a scam. To the best of my knowledge, you could unplug your intake air temp sensor while the car is running and nothing would change. The oxygen sensor controls the air to fuel ratio a little after the car is started.
Now, if the iat did control the afr, it would only run richer, probably giving a couple horsepower since our cars run a lean burn, but it wouldnt be worth it.
Conclusion - all that horsepower adding crap on ebay is mostly false, throttle body spacers, electric turbine fans, etc. Theyve been tested by people with no positive results (that i know of)
Best to stick with i/h/e and upgrades that are proven to work.

... You could buy it for 8.99 and test it, and write up something about it. But it would most likely be a waste aha

 
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Ill just take your word for it lol

From your guy's experience how much of a difference would a intake, cat back, headers make to acceleration? Also how about individually intake, cat back, headers, or even just a performance muffler?

 
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Less backpressure results in worse acceleration (low end anyway). If you want to go faster you have four options: cam, boost, nitrous or swap.

 
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the intake air temp sensor has very little to do with the a/f ratio on these cars. so at worst you would run even richer and waste more gas. you should be adding intake mods to lean out the mix a bit and that will help the most.

 
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You have something in common with the protesters on Wallstreet when it comes to knowing how backpressure works: you are the 99%

OP, the only noticeable gain would be sound. Headers + a combination of catless exhaust would probably gain some results, but likely not remain legal for inspection. On the EX (D17A2) I know the bottleneck is the downpipe, didn't check what you drive.

 
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Then explain, please.

 
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http://www.carforum.net/exhaust-syst...-pressure.html

Power has nothing to do with "backpressure" and everything to do with exhaust velocity, resonance, and a smooth inner wall from manifold to muffler tip.

 
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but larger pipes reduce exhaust and intake velocity. these are slow economy cars we are talking about with less than 100hp.

 
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Actually, the cat transition from the downpipe is the bottleneck. The actual downpipe is the largest diameter section of the OEM exhaust. I agree that headers with a catless exhaust would produce the biggest gains, because that would involve a J-series or LS swap. Seeing that most D17A2s have only one header. I checked what I drive.

Let's not get caught up in the weeds. You seem like you have a lot of good car knowledge. Let's share it without talking down to people. Were not that kind of forum.

 
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Back on point, you can basically do the same mod with 2 wires. This is an old trick used by track jockeys for a while now. Just moves the IAT probe toward the front of the intake vs. near the throttle body. I've made my own test harness to give a try. It works with some success, but I didn't like the look. Mainly for combating heatsoak. Again not a gamechanger for the anemic d17.

 
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im sure you know this, but the downpipe is about half the size of what the outside looks like if you open it and look in there. its about the same as the stock catback piping. im guessing they put a sleeve around it to keep heat in the exhaust so it makes it to the cat without cooling down too much (for the EX). i do not recommend replacing it with aftermarket because then you would lose fuel efficiency and increase emissions. The cat is already too far from the engine as is.

i agree with the iat sensor mod tho, its a good idea and i've had mine like that for years.

 
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My bad. You're absolutely correct. I was thinking of my random tech cat. Fresh in my mind, from working on my exhaust last week.

 
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ive been thinking of ways to get that pipe better insulated, because in the winter it can really run colder than it should. im wondering why they didnt stuff the hollow part with thermal insulation or something. if i had the time and money, i would just get the outside jet coated.

 
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Jet Hot/Ceramic coating definitely would help. The only part of my exhaust not coated is the B-pipe, it always scrapes.

 
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Which is why larger pipes = not always better. Designing a decent exhaust is much like designing a enclosure, fq. tuned and volume accounted, for a specific subwoofer.

Im not talking down, its my sadistic sense of humor

As per what Gearbox wrote, downpipe is the bottleneck.