Upgrading only the muffler to improve sound?

[JThind]

So I've finally talked myself into doing some mods to my car that are beyond tints/trim/wheels. My plan is to start w/ improving just the sound for now, nothing too major with performance yet. Let me start off by saying that my knowledge extends as far as just knowing each part's function within the car. I don't really know what mod goes well with what other mod / where to draw the line based on impact or value/ etc. I know that's probably confusing, so here's a specific example of what I mean:

So I know that the muffler is the single biggest influence to a car's noise. What I don't know is if it would be a good idea to only change the muffler then, or go all the way and change the entire exhaust system. Value-wise, would it be worth the extra money to change the whole system if I don't really care about performance and only care about sound mostly? Or, would the performance upgrade be so substantial that I should do it anyway since I'm going down this road, even if performance wasn't my initial goal?
Basically, I really only care about the noise and would prefer to just upgrade the muffler, but I am not totally against spending the extra money on a full exhaust upgrade IF it would be too stupid for me to stop short of going all the way according to you all. (Or if I'm totally wrong in assuming an entire exhaust upgrade even helps performance, feel free to let me know about how misinformed I am lol).

I typically would have just done the full upgrade, but I only plan to have this car for 3 more years. That's why I'm trying to limit my budget, not because I wanna be cheap about improving my car. I'm willing to go big, but only w/ stuff that would be worth the bug investment in such a short term scope.

[TLR_0125]

Get a cold air intake and do a turbo muffler delete. Replace all ur hoses turbo/ throttle body/ ect to silicone, high performance/diameter hoses for better air flow. You’ll hear very nice sounds from the front. All cheaper than an exhaust system. And be careful with just a muffler, u dont wanna rice up the car probably.


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[JThind]

Get a cold air intake and do a turbo muffler delete. Replace all ur hoses turbo/ throttle body/ ect to silicone, high performance/diameter hoses for better air flow. You’ll hear very nice sounds from the front. All cheaper than an exhaust system. And be careful with just a muffler, u dont wanna rice up the car probably.


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You're def right about not wanting to rice up my car, but I was under the impression that different mufflers make different noises and that as long as I didn't choose some obnoxiously loud, pick-up truck sounding muffler, that I wouldn't be at risk of it sounding like a ricer. Is that not how it works? Or would changing only the muffler and not the whole exhaust always make it sound obnoxious regardless of which muffler I choose?

[snaky69]

You're def right about not wanting to rice up my car, but I was under the impression that different mufflers make different noises and that as long as I didn't choose some obnoxiously loud, pick-up truck sounding muffler, that I wouldn't be at risk of it sounding like a ricer. Is that not how it works? Or would changing only the muffler and not the whole exhaust always make it sound obnoxious regardless of which muffler I choose?

Sound has to do with acoustics and fluid dynamics. If you go with generic, weld-on stuff like Magnaflow (good quality, by the way) a muffler that sounds good on a particular model car might sound like crap on another model.

The exhaust system on this particular car muffles sounds a whole lot. The turbo itself acts as a pretty powerful muffler, the stock catalyst converted is very large and restrictive and further reduces noise, the first resonator is straight through and kills a bit of rasp, the second resonator takes care of cabin drone nicely, and the rear muffler does the rest.

Some people have success (myself included) have success chopping off and replacing parts of the stock exhaust.

I'm running a higher flowing catalyst converter that allows me to run stage 2 software, my large rear resonator had a hole in it and it got replaced by a magnaflow performance muffler. IMO my car sounds like shit on a cold start but sounds very mean once everything's nice and warm.

YMMV.

[Theiceman]

oops ...

[Shuga]

Cut off the muffler and you’ll be happy. The more the cut the louder it gets remember that lol.


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[Shuga]

Get a cold air intake and do a turbo muffler delete. Replace all ur hoses turbo/ throttle body/ ect to silicone, high performance/diameter hoses for better air flow. You’ll hear very nice sounds from the front. All cheaper than an exhaust system. And be careful with just a muffler, u dont wanna rice up the car probably.


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This will make the engine sound weak imo. Make sure you like the sound of the B8 with an intake. If you do then go this route.

It’s all personal preference.


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[A4x]

I've replaced the cat with an 034 HFC and just the rear muffler with a Magnaflow. It sounds good. No drone, nice deep tone. Pretty quiet and I can drive it like the luxury car that it is if I want to.

[Shuga]

Replacing the cat you will most likely get a cel though. Keep that in mind


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[JThind]

I've replaced the cat with an 034 HFC and just the rear muffler with a Magnaflow. It sounds good. No drone, nice deep tone. Pretty quiet and I can drive it like the luxury car that it is if I want to.

1) How much of this improvement do you credit to the high-flow converter and how much do you credit to the muffler? Do you strongly recommend both upgrades?

2) Idk much abt catalytic converters other than not having one is illegal, but are there also restrictions on which types are allowed if you change them? Or do you just have to have one, but doesn't matter which?

3) What is the exact Magnaflow muffler btw? I want to narrow my focus to the models that have been vouched for by Audi owners specifically.

[JThind]

Sound has to do with acoustics and fluid dynamics. If you go with generic, weld-on stuff like Magnaflow (good quality, by the way) a muffler that sounds good on a particular model car might sound like crap on another model.

The exhaust system on this particular car muffles sounds a whole lot. The turbo itself acts as a pretty powerful muffler, the stock catalyst converted is very large and restrictive and further reduces noise, the first resonator is straight through and kills a bit of rasp, the second resonator takes care of cabin drone nicely, and the rear muffler does the rest.

Some people have success (myself included) have success chopping off and replacing parts of the stock exhaust.

I'm running a higher flowing catalyst converter that allows me to run stage 2 software, my large rear resonator had a hole in it and it got replaced by a magnaflow performance muffler. IMO my car sounds like shit on a cold start but sounds very mean once everything's nice and warm.

YMMV.

Gotcha, that makes sense. As far as your car though, are you saying it sounds bad because you didn't change the whole exhaust system and only altered portions? Is that what always happens on a cold-start to cars where you only change the muffler/resonator/etc and not the whole system?

Or is that just because of the specific muffler and how it bodes with your car, as you were explaining in the first half of the message?

[Mia80]

Gotcha, that makes sense. As far as your car though, are you saying it sounds bad because you didn't change the whole exhaust system and only altered portions? Is that what always happens on a cold-start to cars where you only change the muffler/resonator/etc and not the whole system?

Or is that just because of the specific muffler and how it bodes with your car, as you were explaining in the first half of the message?

Good Q JThind, would like to hear about this so I understand better :)

[snaky69]

Gotcha, that makes sense. As far as your car though, are you saying it sounds bad because you didn't change the whole exhaust system and only altered portions? Is that what always happens on a cold-start to cars where you only change the muffler/resonator/etc and not the whole system?

Or is that just because of the specific muffler and how it bodes with your car, as you were explaining in the first half of the message?

I’m just a mechanical engineer that likes cars a lot. I’m not well versed enough in that part of engineering to actually know for a fact the answer to that.

My educated guess is that it’s a bit of everything. On a cold start most engines will run at a much higher idle speed and inject extra fuel to get catalyst converters up to temperature as fast as possible.

The high flow catalyst that’s on there is larger in diameter throughout and the catalyst element lets a lot more exhaust gases through. Combined with the higher idle and cold exhaust piping I’m guessing it causes some kind of resonance while everything warms up, most likely from the first resonator.

I don’t get any weird noises on a warm start.

[A4x]

1) How much of this improvement do you credit to the high-flow converter and how much do you credit to the muffler? Do you strongly recommend both upgrades?

2) Idk much abt catalytic converters other than not having one is illegal, but are there also restrictions on which types are allowed if you change them? Or do you just have to have one, but doesn't matter which?

3) What is the exact Magnaflow muffler btw? I want to narrow my focus to the models that have been vouched for by Audi owners specifically.

1) Impossible for me to say. I only mentioned the HFC because I wanted you to get the whole picture of my exhaust system. I think if you just replaced the rear muffler with a Magnaflow you would like it. It will still be quiet, just it will sound a little deeper.

Honestly the biggest difference in exhaust note came from just tuning my car. I couldn't believe how much more aggressive it sounded from the tune (more airflow through engine and exhaust). Stage 2 was a huge jump from stock, and K04 another jump.

2) No idea.

3) MF 12158. Just a simple straight thru muffler with single inlet and dual outlet. I use the ECS 3.5" tips and they fit nicely in the valence.

[snaky69]

1) How much of this improvement do you credit to the high-flow converter and how much do you credit to the muffler? Do you strongly recommend both upgrades?

2) Idk much abt catalytic converters other than not having one is illegal, but are there also restrictions on which types are allowed if you change them? Or do you just have to have one, but doesn't matter which?

3) What is the exact Magnaflow muffler btw? I want to narrow my focus to the models that have been vouched for by Audi owners specifically.

As far as 2 goes, removing or replacing any part of the emissions equipment is illegal, so even a high flow cat isn’t technically allowed on public roads.

[Shuga]

As far as 2 goes, removing or replacing any part of the emissions equipment is illegal, so even a high flow cat isn’t technically allowed on public roads.

And? If you pass inspection it’s legal enough...


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[snaky69]

And? If you pass inspection it’s legal enough...


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You do love to argue over semantics.

Notice I said technically, whether an inspector would flag you for it is up to him or her. We don’t have such inspections in my part of Canada, but the law is similar.

[Shuga]

You do love to argue over semantics.

Notice I said technically, whether an inspector would flag you for it is up to him or her. We don’t have such inspections in my part of Canada, but the law is similar.

Arguing over semantics is my thing

Personally over in NY they just plug the car in, if you get all green you’re good to go. It’s not something that requires a visual inspection at least not for the undercarriage.


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[BeerBrent]

I've been thinking about replacing my two rear mufflers in my avant with Magnaflows, everything else stock. Just want a little bit more sound. Anyone know the Magnaflow part # for the avant exhaust?

[Theiceman]

You should be able to put a high flow cat on no problem as long as you have the o2 sensors connected without a spacer and communicating with the ecu. There is no law saying you can not put on an aftermarket cat, oem or other, but it must satisfy the conditions of OBD2 and not throw a code.

[KEV_19]

I replaced the large resonator under the rear seats with a straight pipe and was very happy with the sound. I ran with just that for about 8 months and was very satisfied because it only cost $80. Its not too loud by any means and very little to no drone. You’ll get some nice DSG “burps” on upshifts (if you have the DCT auto). It was basically silent on idle and cruising but made great noises on acceleration to accompany the K&N cold air intake up front. Recently I replaced the stock cat with a 3inch test pipe and those little burps became AK-47 gunshots it’s super loud with the res delete and smells pretty bad but makes me smile every day. It threw a check engine light immediately but a tune from IE or APR will get rid of it.