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Discussion Starter · #1 ·
Hi everyone

Just thinking about what I could do with the up, and thought about the exhaust.

I'd like a different note from the engine, something different but not full on Corsa at McDonald's (ugly and loud).

A friend of mine got an exhaust around November time, costing about £300. It sounds really nice and all, but I don't think I could bring myself to spend so much money on a car that might not be worth it in a few years.

So I was looking at an image of the exhaust and noticed the great big resonator right in the middle.

I was just wondering if I were to remove the resonator, and put in a different diameter pipe, or even a pipe the exact same size as the rest of the exhaust, is there a predictable noise that the exhaust may make or is it totally up in the air how it might sound?

I'm totally new to modifying exhausts but hearing resonator deletes on things like Golf GTIs has done them so much good, I wonder if it could do the same to the up.

Photo attached is, to the best of my knowledge, the VW up! naturally aspirated exhaust with the giant dorito in the middle.

Thanks!
5062
 

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Hi there, I would love to know whats the outcome too. I have the same exhaust on my Up. I was thinking of the catback method too. Saw a couple of videos on youtube (
) this link should give you an example of what I think it would sound like, or what I hope to achieve. Nonetheless , let me know what works for you. I would like to do this soon too
 

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Hi Custard,
I can't speak to exhausts specifically (though great to see what is most likely on the underside of mine in real life, not just in two half-drawings), but I can comment a bit on sound generated by air moving through pipes...
Picture any wind-based instrument that comes in a range of sizes (woodwind, brass, organ, humans). I will use the recorder as an example since most UK children encounter it at school!
5064
(from Wikicommons)

Small ones make a high-pitched noise, and are both short and narrow. Big ones make lower-pitched noises, and are longer and wider. So the pitch (frequency) of the noise will change depending on both how far the air has to travel, and how fast the air is travelling, through the system (recorder, exhaust). Longer/wider paths also require more air moving through them to make the same volume of noise.
I am guessing that the resonator on the exhaust system is like the reed on some woodwind instruments, such as clarinets:
5065
5066
(both from Wikicommons)
They make a noise by passing air over the reed, making it vibrate. These vibrations are transferred to the air, and the tone of the sound is then modified as the air passes along the length of the instrument (with the same effect described before for the recorder). If you remove the reed from these instruments and then try to play them, they will either make a vague breathy sound or nothing at all. My guess is that something similar happens with the resonator deletes you mentioned.
On a car you also need to keep in mind that the system is there to get gasses away from the engine so it can work properly, as well as remove toxic/pollutant gasses in the car, so there will be limits on where/how much you can change the length and diameter to ensure the appropriate flow rate is maintained. As far as I can tell from ETKA, the Up! has a 2-stage cat (the coil-covered bit at the front and the 'dorito' at the back, in your photo), so I don't think you can just remove the dorito and replace it with a length of pipe. But clearly people can/do modify the exhaust and still pass their MOTs, so over to them for the car-specific info!
Front half:
Rear half:
 
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Discussion Starter · #4 ·
Hi there, I would love to know whats the outcome too. I have the same exhaust on my Up. I was thinking of the catback method too. Saw a couple of videos on youtube (
) this link should give you an example of what I think it would sound like, or what I hope to achieve. Nonetheless , let me know what works for you. I would like to do this soon too
Hi

That sounds decent. Obviously, phone microphones might dumb it down and whatnot, but even that is nearly pushing it in terms of what I want my exhaust to sound like.

I don't think I'd go for a full cat-back, just a smaller or same diameter resonator swap-out.
 

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Discussion Starter · #5 ·
Hi Custard,
I can't speak to exhausts specifically (though great to see what is most likely on the underside of mine in real life, not just in two half-drawings), but I can comment a bit on sound generated by air moving through pipes...
Picture any wind-based instrument that comes in a range of sizes (woodwind, brass, organ, humans). I will use the recorder as an example since most UK children encounter it at school!
View attachment 5064 (from Wikicommons)

Small ones make a high-pitched noise, and are both short and narrow. Big ones make lower-pitched noises, and are longer and wider. So the pitch (frequency) of the noise will change depending on both how far the air has to travel, and how fast the air is travelling, through the system (recorder, exhaust). Longer/wider paths also require more air moving through them to make the same volume of noise.
I am guessing that the resonator on the exhaust system is like the reed on some woodwind instruments, such as clarinets:
View attachment 5065 View attachment 5066 (both from Wikicommons)
They make a noise by passing air over the reed, making it vibrate. These vibrations are transferred to the air, and the tone of the sound is then modified as the air passes along the length of the instrument (with the same effect described before for the recorder). If you remove the reed from these instruments and then try to play them, they will either make a vague breathy sound or nothing at all. My guess is that something similar happens with the resonator deletes you mentioned.
On a car you also need to keep in mind that the system is there to get gasses away from the engine so it can work properly, as well as remove toxic/pollutant gasses in the car, so there will be limits on where/how much you can change the length and diameter to ensure the appropriate flow rate is maintained. As far as I can tell from ETKA, the Up! has a 2-stage cat (the coil-covered bit at the front and the 'dorito' at the back, in your photo), so I don't think you can just remove the dorito and replace it with a length of pipe. But clearly people can/do modify the exhaust and still pass their MOTs, so over to them for the car-specific info!
Front half:
Rear half:
plancast back at it again with the science ;)

As far as I am aware (however may be wrong as I am not an exhaust technician) the resonator does more for sound levels than it does for emissions - I suppose it does what it says on the tin - the resonator resonates. I think I might go for a larger but still less boring pipe too - just to be on the safe side of not sounding like a Honda Civic!
 

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Discussion Starter · #6 ·
Well everyone, time to close the thread, as the gentleman in the video said, all he did was remove the middle silencer! Nope!!!!
 

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Discussion Starter · #9 ·
I can tell you exactly what happens when you do that, it drones like crazy and will drive you mad within hours (experience talking).
I don't doubt you at all!

I'm now looking at speaking to a custom exhaust company to fit a customised, shorter resonator - I think this might give the best of both worlds, but again, I'll just be keeping an eye for now.
 

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I don't doubt you at all!

I'm now looking at speaking to a custom exhaust company to fit a customised, shorter resonator - I think this might give the best of both worlds, but again, I'll just be keeping an eye for now.
This sounds great!

Please do share what your experience. Pictures would help
 

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My 2012 up has had exactly this done to it. Took out the massive middle muffler and replaced it with a smaller diameter (almost the same as the main piping) resonator. There's a much deeper note to the exhaust and I love it. When pushing through 2nd you get a really nice note to the exhaust, and it crackles and pops like nothing else through 1st, 2nd, and 3rd. It is loud, and can be obnoxious up hills, but it's perfect to me.

I would take a video to show you but I've currently got the gearbox out :)
 

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My 2012 up has had exactly this done to it. Took out the massive middle muffler and replaced it with a smaller diameter (almost the same as the main piping) resonator. There's a much deeper note to the exhaust and I love it. When pushing through 2nd you get a really nice note to the exhaust, and it crackles and pops like nothing else through 1st, 2nd, and 3rd. It is loud, and can be obnoxious up hills, but it's perfect to me.

I would take a video to show you but I've currently got the gearbox out :)
That sounds great, how/where did you source the new resonator from or was it a custom job? i have debated a custom exhaust (naturally aspirated Up) as well but from past experiences such small engines run terribly at low rpm without the additional back pressure...

P.S why is your gearbox out? it seems like they are the weak point in the Up, probably made of paper, and the 6 speed GTI box's are like gold dust so id be really interested to know if anyone knows of gearbox mods or up-rated internals??
 

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As above, he's just taken the middle silencer out, he'll be deaf soon if it stays that way, from the horrendous drone, especially on the motorway.....
 
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