Most do give a slight boost in performance, but I suppose it's your call as to whether it's worth the money... You probably wouldn't be able to notice the difference in power.

Assuming nothing else has changed on the car, then depending on the design, the answer varies from "slight but negligible" to "it actually hurts performance." Normally aspirated cars do benefit from a specific range of exhaust velocity in order to achieve a scavenging effect during cylinder blowdown, and having a big, open pipe in the back takes away that advantage by reducing exhaust velocity. However, if they've had engine work done, then chances are a bigger-than-stock pipe is helpful in regaining the balance that was altered by the engine mods. It's doubtful that most exhaust-modded Civics are in this category though.

In simple words a stock civic would not gain performance with one of those noisy mufflers. A Civic with a highly modified engine (intake, turbo, super charger, camshaft, increased compression ratio) would benifit from the noisy muffler. Those mufflers are desighned to increase the amount of exaust that can flow out, however a civics factory exaust system is capable of handling the exaust flow out of a unmodifed engine. Hence unmodified engine no performance change. Modified engine performance improvement.

Yes, even on stocks. After the exhaust leaves the exhaust valves from the engine, it leaves through an exhaust system. The exhaust system includes an exhaust manifold, catalytic converter, and a muffler. Mufflers are designed to cancel out sound and were not considered within performance. Some stock mufflers produce back pressure which is the pressure built up in the exhaust manifold, because the muffler is narrow and all the exhaust cannot escape from it as fast. Backpressure slows down the engine in the exhaust stroke of the 4 stroke system by making it harder for the pistons to push up to release the exhaust, this decreases the piston’s momentum and slows it down, and the piston would have to gain its original momentum again through another combustion. Most stock mufflers produce back pressure. So by having a bigger muffler you would gain hp. Keep in mind that having a very big muffler actually decreases performance. Muffler size depends on the RPM of your engine.

if it was the only performance enhancer on the car technically it would slow it down cause its heavy .

You have definetely hit on a hot-topic with this person. Those big, noisy mufflers do not improve performance, they only add to noise pollution. i write a citation to every vehicle i hear or see. these so-called mufflers, are ear- shattering. To my amazement, most drivers do not believe the mufflers are a law violation. they tell me the muffler shop said, "it sounds good and is within legal noise limits". not true. i wear hearing aids and its partially due to loud auto mufflers. I allow some to go with a warning, providing they have not been "showing out" with the muffler. meaning, reving the engine to full throttle thru each gear shift, just to make noise. I do not believe these mufflers have noise resonators inside. they may have come that way from the factory, but i guarantee they have been "doctored" or the insides taken out. I particulary watch for these vehicles for one reason: i have learned, that a person driving a vehicle with a loud muffler, usually has other traffic violations or warrants outstanding. do not know why. The owners of these loud mufflers are issued a citation. i issued 5 muffler citations to the same driver/car, on 5 different dates, for the same muffler violation. he was determined not to obey the law. this cost him over $2,000 in court.

If you have a bigger intake and other bolt on such as: headers,bored throttle body, intake manifold. With the exhaust, it will help with the airflow. Stock muffler is like drinking with a straw and with the performance exhaust, it is like drinking straight from the bottle.

If your Civic is stock, then that 115mm exhaust tip isnt doing anything at the end of your car. The airflow from the cylinder to the exhaust might be smoother, but then again Honda has stock catbacks for a reason. If you made mods to the engine, like camshats, or bigger cylinders, with a supercharger then that exhaust will improve airflow, and exhaust performance, but for the most part most people, just bolt on a intake and maybe a turbo , so if your not making major mods to the enigne then theres no use for that exhaust tip.

Every one that has a loud muffler is a A--H---. Why do you need a loud bumble bee for a car ,its not impressive to anyone and all it does is make noise pollution.Waste your money much?Most of these cars that have them have STOLEN parts and should be impounded! The cop issuing the tickets deserves a commendation.

Most don't. A well built up Honda does sound good. I tell you to all you people who bitch and moan about being annoyed by these, to sit down and shut up. It's a form of expression and it's in the eye of the beholder. I have had many loud v8 mustangs in my time and there is nothing wrong with rumbling down the street. I'm all for loud cars except for my daily driver. I have a 2004 civic, it's bone stock. It will be staying this way because on the other side of the coin, it's nice to get into a silent car to drive an hour and a half down the highway.

not nearly as much as they think they do

they don't unless you are willing to and intake, upgrade fuel, and add full exhaust system including headers. then it will gain HP.

To those who are getting angry at the people who have loud exhausts should ignore it. IMO these people just have it because to them, they like the sound and it gives them a more enjoyable drive. So just let them be and to those who will say "The sound hurts my ears." Stop being a pussy.

A little bit, but all those glossy sales pamphlets overpromise the gains. Why not just stab a couple holes in their current muffler, it'll still have about the same effect. Besides, those drivers are usually alone, so it isn't as if they need to have it quiet enough to have a conversation with passengers.

lets say I want to put a three inch exhust into my Honda civic and leave out the cat do I have to put my o2 sensors back in like weld new bolts holes

I agree with the cop because there's a knucklehead who lives down the road from me who drives by all the time with that muffler blasting in his red corsica with a worthless spoiler. He punches the throttle to make it louder and he is doing 50 in a 30 MPH zone. He does this every 20-30 minutes til 2 AM sometimes and he also wakes up our baby. I am going to get this guy. And yes he IS hurting somebody. He is waking people up who work in the morning.