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Old 12 Nov 2011, 06:18 pm
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Default Will Straight pipes do anything performance wise to my civic?

i have a 2004 honda civic ex sedan with a 1.7L 4cylinder VTEC engine. I just got straight pipes installed (2 1/4in pipes) with a huge ass muffler. Will this do anything for performance (hp, mpg). I heard it will increase hp because of less back preasure but im not sure.

The muffler dulls a lot of the sounds so its not obnoxious at all. Its just a deep throaty muscle car type sound
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Old 12 Nov 2011, 06:31 pm
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You want the truth? You might gain a few 1-5 hp. Maybe. I almost forgot the other poster reminded me, you will probably loose some power throughout the power band due to loosing some needed back pressure. In the end you gain a noisy/slow car that people like me laugh at.

You want actual power?

There are only 2 choices

1. Get a built honda motor eg b or k series (few grand) Boost it correctly (3-6 grand).

2. Sell it and get a fast car.

My favorite honda story: My roommate who drives a Cobra, was driving his dads diesel truck, well long story short he ends up racing a 00 si modded or something like that and destroys it in the F250 with a full cab. LMFAO
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Old 12 Nov 2011, 06:46 pm
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Not likely.

Just remember, a certain amount of back pressure actually increases performance by keeping the expanding gasses pushing against the cylinder (exhaust valves open before Bottom Dead Center). Otherwise it just blows out the back.

That loud noise you hear? That is power being turned into sound!
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Old 12 Nov 2011, 07:01 pm
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Posts: 630

yes, little more power as there is less resistance w/out cats...maybe 5 or 6 hp gain.....

youll probably piss off neighbors, not pass inspection and need Advil while driving though
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Old 12 Nov 2011, 07:16 pm
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NOOO!!!!, ANd it'll sound like crap!!!
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Old 12 Nov 2011, 07:31 pm
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It can decrease power because it will actually increase back-pressure if the exhaust changes size - either larger or smaller - between the collector and the muffler internals. Any change in back-pressure is a bad thing because in some systems it can increase EGR at low rpms (see source 2, pages 20-23). The best exhaust is one costing very large money; otherwise the stock exhaust setup is your best bet. Honda spent hundreds of thousands, possibly millions of dollars designing the stock exhaust. You are not going to do better without spending a *whole* lot of money.

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