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IainR

130i Exhaust Mods by Previous Owner?

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Hi guys,

Recently bought a 130i as my first BMW and loving the experience so far. I'm just starting out the journey of finding out what modifications the previous owners have made. At the moment, it's the exhaust system that has my attention. I'm aware that it has the MSport Performance muffler but can anyone shed some light as to whether or not the system has been further modified (cats removed etc)?

I'm a bit torn with the current exhaust setup as it drones a little too much for my tastes while cruising around but I adore the sound while on full throttle!

I'm a little embarrassed by the quality of the photos added but these aren't the easiest cars to crawl under!

 

Any comments appreciated. Let me know if I need to get back under the car for better pics.

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IMG_20200401_133440.jpg

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The cats are up the front, are part of the exhaust manifold. That weld just aft of the heatshield isnt normal (from memory), but there isnt anything there normally anyway. There is a resonator up further that takes the 2 pipes from manifolds and collects them to the single exhaust that is a common mod to remove and replace with a straight Y pipe without a resonator.  

There is no Msport performance muffler by the way, its a BMW Performance muffler (was a dealer option thing rather than an Msport option thing). If you get a pic of the part number/dataplate will be able to work out if its BMWP or a 135 unit.

 

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Cheers Jacko!

Just back from getting a couple of extra pics: Information plate from the muffler and the Y-Pipe.

Any guesses on the main culprit for the drone? If i want to keep the brilliant noise from the Straight 6 on full throttle am I going to have to keep the slightly anti-social exhaust note while driving around at neighourhood speeds?

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sh*t welding and maybe something touching. Some of it looks close to the heat shields.  Hard to say from the photos. Better looked at on a hoist or high setting axle stands

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I did notice the welding 😐 As long as no gases are leaking I don't mind it too much.

I agree that it'd be good to get it up on a lift but that'll have to wait until this lockdown is over.... 

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Yeah the Y pipe has been done, which will be the cause of the drone. General rule of thumb is back box or Y pipe resonator delete, not both :) As Glenn says its not pretty work. 

Options will be to find a stock 130 exhaust and bolt it back in, going back to having a centre resonator, or ditch the BMWP backbox and finding a stock 130 one. 

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Just the info I was after! 

As soon as i bought the car, I grabbed a stock 130i muffler off Facebook for $80. Just in time for lockdown 🙄

Reckon I'll get it fitted when I can and hopefully I won't lose too much of the engine scream but in turn fly under the radar while driving around quiet neighbourhoods. 

 

Thanks again! 

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If it were me I'd keep the Performance back-box and add a single resonator forward of the Y pipe and fix up those welds at the same time.

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21 minutes ago, M3AN said:

If it were me I'd keep the Performance back-box and add a single resonator forward of the Y pipe and fix up those welds at the same time.

Agree - this would preserve what you’re after and those welds are very untidy. 

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Cheers for the input guys. 

 

Would a resonator be an off-the-shelf or specialist item? As you can tell, I'm not totally clued up on exhaust systems! 

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Any exhaust shop will be able to size a suitable resonator, it should be off the shelf. You probably want to add one to each pipe... shop should advise you on that, I have no clue. <- that's irrelevant, the resonator would go between the Y-pipe and the muffler, on the single pipe section.

What you want your Y pipe to look like:

Exhaust07.jpg

Edited by M3AN
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Nice one. Thanks for the help guys. Much appreciated! 

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On 4/2/2020 at 12:06 PM, IainR said:

Nice one. Thanks for the help guys. Much appreciated! 

I've corrected my post above, you'll only need one resonator, it will go between the Y-pipe and the muffler, where the heat shield is. But get the Y-pipe sorted at the same time regardless.

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The saga continues.....

I dropped my car off recently to a muffler shop and explained my issue with the drone. The photo below shows what was fitted (not a muffler, I can't remember what he called it). To be honest, I don't really notice any difference from how it was before. 

I swung by the same shop to see what else could be done and he reckoned I really need to get my hands on the oem centre pipe with muffler intact to make a real difference to the sound. 

Do I take this as gospel and start the hunt for original (2nd hand) bits or try a different shop?

 

The photo is taken from underneath the backbox pointing towards the front wheels - just in case it's not obvious! 😁

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It looks like a resonator, does that ring a bell?

It's in the correct place and should have attenuated the noise somewhat.

I think their advice however is poor, there's no point in finding and putting a stock section in there, you could just add aftermarket parts to the same effect. But really, that resonator should have done the trick or they should have used a different resonator (i.e. it sounds like they installed something that doesn't do what you asked for, surely that's their problem?).

If you feel you have no options, the next step I'd take is to replace the BMWP muffler with the stock 130i one you purchased. I've not checked but that could be a bolt on exchange (i.e. no welding required, possible to do it in your driveway). If you can swap them over and you like the result then you'll have a BMWP muffler to sell which is very valuable and will probably recover all your costs to date.

I'd be interested in hearing and audio clip or video of your exhaust as it stands now... here's mine (full custom exhaust without resonator). Poor quality but you'll get the idea, is yours louder than this?

https://www.davesanthology.com/public/images/automotive/e87/130i/Exhaust/OW_Exhaust.mp4

 

Edited by M3AN

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I'll backtrack slightly. The invoice says 'cnc muffler'. We spoke on the phone after he had initially had a look at the car and had said this part was my best bet. No guarantee was implied as to it being the perfect fix so I don't feel I have right to make it his problem. 

When I re-visited the shop, I had the stock rear muffler in the boot but he reckoned it wouldn't do the job and the centre section was the issue. Unfortunately, the stock muffler has been chopped by whoever removed it so some fabrication is definitely required. 

 

Nice video! I'm not totally sure how different mine is. I'll have to grab a clip this weekend. 

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Understood.

Hmmm... I don't think getting a centre section alone will work, I can't tell from your pics if will even match up with the front section.

It might be worth calling around some wreckers to see what the cost of a full (3 sections) stock 130i exhaust might be (if you can find one). I have no idea what that might cost but I'd be surprised if it were more than $600 (should really only be about $300). Then you could sell your (new) resonator centre section and your BMWP muffler. The centre with resonator would probably go for ~$150 to the right buyer (what did you pay to get the resonator installed?) and the BMWP muffler is worth over $600 by itself to the right buyer (IMHO).

Whatever you do, don't damage the BMWP muffler, they're no longer available and highly desirable.

Edited by M3AN

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1 hour ago, M3AN said:

what did you pay to get the resonator installed?

Just over $300.....

 

Don't worry, I have no intention of meddling with the BMWP muffler. I've become aware of how hard they are to come by!

 

Thanks for your help @M3AN 

 

I reckon I'll swing by another shop and be more direct with what I'm after and see what they suggest but I'm not inclined to spend much more to gamble on the outcome! 

 

 

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Id just go grab a replacement exhaust from the manifold to the back box from a wrecker, there will be a few of them out there and I doubt it'll cost much.. Id say less than $300 :D  (I suspect they're not that sought after, apart from people in your situation)

And then with some new gaskets you can bolt it in in the driveway, and it'll sound like BMW intended 

As modelled by the dog - 

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Edited by Jacko
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15 hours ago, IainR said:

Just over $300.....

That's a fair price, you didn't get gypped.

 

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You need a center muffler if you want to make it quieter.  Resonators won't do sh*t unless they magically nail the right frequency.

 

edit:  I still think there's a gap in the market for someone that can crunch the math and make exhausts with hemholtz resonators to eliminate drone using standard materials to keep costs down.

Edited by GorGasm
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A short clip of the exhaust. I quite the like note in the video but it doesn't highlight drone when the engine is under load. 

 

The hunt is on for a centre section. I actually found one in a wreckers yard in Wellington but it is on a 130i with over 130k and has definitely seen better days! 

 

A shor

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Yeah, that does sound as I'd expect it to, pity about the drone... can't use a different gear?

 

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Nah, I get the drone regardless of gear choice. It wouldn't be so bad if I didn't live somewhere as hilly as Wellington 😂

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Just having a peak around the car and shined my torch down the tail pipes. I see there's an open butterfly valve in the LHS exhaust. Is this right or should it be closed until Im at higher revs or WOT? 

I've tried researching the operation of the valve but can't quite work out exactly how/when it's meant to be open or closed. 

 

Thanks for letting me pester you all with this topic! 

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