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I have 3 devices under my car connected to my exhaust, but I dont know what they are or what to do about them? Answered

I have 3 devices under my car connected to the exhaust system. Im unsure about what they are, what I can do about them, or how I can modify these to make the car louder,lighter,and less restricted.

The car is not broken and doesnt need repair, this is about modding it. My biggest concern is the last device (3rd picture), because it is big, and most likely heavy. I know the exhaust system will restrict the engine, I also know that the exhaust system has a muffler and a catalytic converter.

So my question is   What is this device in the back? How can it be removed/bypassed/replaced/modified to be louder lighter and less restricting? And if I cant do anything with it, what can I do?
(the devices are in order from closest to engine to farthest)



6 years ago

cheapest and most effective loud thing u could do (while keeping back pressure in mind) is put a Y- right before the muffler. the base would connect to the piping from the engine, one of the "arms" goes the the muffler, and the other arm runs to a butterfly valve. then if u want it loud, open the valve and exhaust will bypass the muffler, or if your picking up your grandma, you can close it and make all the exhaust go out the muffler.

Wow. That's an ingenious idea. I may have to put a smaller secondary muffler on the other end to still keep the back pressure up. I have a few questions though

How would I mount the new exhaust system to the chasses?
How would I control the valve?
How would I modify the system? I.e. What tools, materials, knowledge would I need to do this

I would do a google search of "exhaust bypass valve" and see what u get. For exsample, on the top of this page is a good example of what i'm talking about http://www.superstang.com/powered_exhaust.htm
most of the time they are controlled electrically, and you shouldn't really need to create a new mounting system.
it's really more of a cut a short section out of ur exhaust pipe before the muffler, add in the bypass valve, and weld or hose clamp (must do this really good or it'll slip off) it on.
also, if you just want a better performance, try looking here https://www.instructables.com/id/PERFORMANCE-EXHAUST-DIY-2010-CHALLENGER-RT/
hope this helps

thank you.
Im confident that this would help :D

It's very hard to tell what you are talking about, with such small photos.

If it's electrical probes, then they're part of the engine management system, testing the waste gases to control the engine.

The pipework, if you change that, can cause problems with the "back pressure", changing the way the engine burns.

In other words, don't break what you take off, just in case you need to put it back.

back presure?

very ture but that same rule applies to just about everywhere else too

You want 'less restrction' on your muffler? As kelsey and Kiteman are trying to say, you NEED a certain amount of pressure in the exhaust so the engine functions properly, or it's timing goes wonk and you LOSE power.

i certainly dont want power loss. how can I know what the right presure for a car like this is?

That's for the pros to decide. Honestly I'd stick with factory exhaust unless you're specifically racing it around a track.

no raceing, the car is for standard driving purposes, and honestly just wanted to make it mor fun to drive

Leave it stock :) It'll be plenty of fun.

Is your car fun now? then leave it how it is.

For 1-200 dollars I'd recommend a high flow air filter, that's about all you're going to be able to change.

for the most part it all depends on how its driven

thats all I will be able to change because of my low automotive skillset, or because of the car itself?

.  With modern engines, you are not going to be able to get an appreciable amount of extra power with cheap bolt-ons. More than likely, you are going to actually decrease performance (unless you have an automotive engineering background). The only way to tell for sure is on a dynamometer and it doesn't sound like you have to money for that.
.  You can also buy a pre-engineered cat back system, but, once again, it doesn't sound like you have the money for that.
.  If you just want more sound and are not too concerned about performance or gas mileage you can remove the resonator. Save all the parts in case you don't like the sound. Or buy a louder muffler - but that's money you don't seem to have.

right, moeny is definatly an issue here. what money i do have would be put into that. i do want a louder sound but what if i dont care about increasing proformance and want to keep it close to where it is now?

Back pressure.

If you plan to search for something online, it helps to spell correctly (computers aren't as smart as humans).


7 years ago

If your car has to pass emissions testing prior to registration, messing with your exhaust system is not a good idea unless you know exactly what you are doing and what the emission standards requirements are for your state. In some states any alteration can automatically disqualify the vehicle for registration. Furthermore, one or more of those devices are sensors that sample the exhaust gases and feed that information to the vehicle's computer system to automatically adjust for emissions and fuel economy.

the last muffler has no sensors or wires it simply hungs suspended under the car with rubber shock absorbers then imediantly exits the exaust (not seen very easily in the pictures)

Before removing the muffler, you will want to check with your local jurisdictions (including any others through which you may choose to drive), to find out what ordinances they have regarding vehicle noise.

Of course, if you have the money to throw away on fix-it tickets, that's your choice.

in my area (north and south carolina border), i find many cars with moddifications to the exhaust system, living here for nearly 6 years, the signs of the car getting quieter are not found

:-) It really does depend on jurisdiction, and also on what the local police choose to enforce or not (i.e., what resources to they have). In L.A., I only saw those sorts of things enforced if someone actually called in a complaint.

i think thats how it is here (sc) too. nobody ever calls in a complaint normaly because they would be at fault as well for something similar

If you want to mess about with the exhaust, take everything off. Why keep any of them?
You'll probably have difficulty with the electrical probes though, how many of them can you see?


on the catalytic converter just 2 (one on either side) but after that there arent any electrical probes only pipe work

You've got some good answers here, but see how the car runs with the probes disconnected, you could have a problem with removing the cat'.
Have you looked at buying a purpose-built exhaust-kit?


I have not, although ive heard theyre expensive

.  First pic is the catalytic converter.  Required by federal law.
.  Second one is a resonator (AKA, just another muffler). Gives a "better" sound.
.  Last one is the muffler.
.  You can legally change anything from the catalytic converter back, but just because you can doesn't mean it's a good idea. Modern engines and their control systems are designed to work best with the factory exhaust.

ok thank you

there are lots of cars in my area that have that low pitched "rumble sound" that would only come from after market exhaust systems, right? so i dont think it is problem here.

.  That low-pitched rumble can be caused by many things. A big-block V-8 has that sound even with a restrictive exhaust system. Few four-cylinder engines will ever achieve that sound.
.  I'm not sure what "it" is or where "here" is, but I don't think it really matters. If you mess with any part of the drivetrain on a modern car, you stand a very good chance of having a negative impact on performance and milage. If you don't have some idea about how cars work, your chances of screwing up increase.
.  If you want to change the sound of your car, do not start deleting/adding/modifying parts willy-nilly. Investigate what are commonly called "cat back" exhaust systems. The good ones aren't cheap, but that's the price you pay for driving a modern car. If you want to futz around with the drivetrain, buy a carbureted muscle car from the '60-70s.

And you can get higher-flow low-restriction catalytic converters, they cost a pretty penny though.

I have a 'racing' exhaust on my car designed to make it as quiet but less restrictive as possible...It does give a performance boost but did make the car an order of magnitude louder. Thank god it doesn't sound like those "low" fart pipes.

I dont want a "low fart" pipe either. Id prefer a steady hum.
l also have very little to no income so money is an issue here. I was hoping i could get somtheing around $100-$200


looking at those prices I'd say hold on to your money.

i have a 4-cylinder engine, so there will be no V-8 power coming from it. however my grandfather has a 4-cylinder engine car from '92 I beleive, with a moddified exhaust system that has the ideal sound to it. His exhaust system is far differant to mine.

"it" is the moddification
"here" south and north carolina

unfortunatly this is not a car from the 70's-80's. this is a 2011 mitsubisi lancer, Im begining to think this isnt going to be very easy to moddify anywhere on the car

Cat, resonator, muffler.