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Tony Tsui

N54 Decatted Downpipes???

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Hi guys, I own a 2007 335i and I'm wondering if there's way to figure out whether the downpipes has already been decatted other than taking it off and check.

Reason for that is because when I checked underneath my car all the pipes look to be stock but it sounds louder than other 335s I know with the same MHD tune settings. And in MHD under both Oxygen Sensor and Oxygen Sensor Heater are incomplete. I've owned the car for a year and it's always been showing the same info.

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There should also be a code and the associated check engine light, assuming you haven't enabled the MHD flash setting that clears it. If you have, re-flash the map without the catless option or flash back to stock, and see if it comes up after driving a bit. 

But I'd say that's a good indicator it's catless. Catless downpipes make a very obvious difference to the sound, it's about twice as loud as stock. 

For the sound, it's also possible the 'PE mod' has been done. Look at the top and bottom of the mufflers to see if they've been opened up before, you'd see welds from it being sealed back up. Google the PE mod to see what to look for. 

Edited by Matth5
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22 hours ago, Matth5 said:

There should also be a code and the associated check engine light, assuming you haven't enabled the MHD flash setting that clears it. If you have, re-flash the map without the catless option or flash back to stock, and see if it comes up after driving a bit. 

But I'd say that's a good indicator it's catless. Catless downpipes make a very obvious difference to the sound, it's about twice as loud as stock. 

For the sound, it's also possible the 'PE mod' has been done. Look at the top and bottom of the mufflers to see if they've been opened up before, you'd see welds from it being sealed back up. Google the PE mod to see what to look for. 

So on MHD the option is OEM/Catted DPs, and I have always had it checked. Did you mean that I should uncheck it and see what happens?

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23 hours ago, Matth5 said:

There should also be a code and the associated check engine light, assuming you haven't enabled the MHD flash setting that clears it. If you have, re-flash the map without the catless option or flash back to stock, and see if it comes up after driving a bit. 

But I'd say that's a good indicator it's catless. Catless downpipes make a very obvious difference to the sound, it's about twice as loud as stock. 

For the sound, it's also possible the 'PE mod' has been done. Look at the top and bottom of the mufflers to see if they've been opened up before, you'd see welds from it being sealed back up. Google the PE mod to see what to look for. 

I've got a few clips here if they tell anything, my burble aggressiveness setting is on hard and it sounds way louder than my mates 335i with the same settings.

Edited by Tony Tsui

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3 hours ago, Tony Tsui said:

I've got a few clips here if they tell anything, my burble aggressiveness setting is on hard and it sounds way louder than my mates 335i with the same settings.

Hmm I'd say that's either catless or something is done to the exhaust, if you can't see any signs of the PE mod. That doesn't sound like a PE mod/exhaust to me so I'd lean towards it being catless. 

"So on MHD the option is OEM/Catted DPs, and I have always had it checked. Did you mean that I should uncheck it and see what happens?"

With it checked it should still trigger the codes just like with stock. You should have a check engine light and some fault code(s) about emissions. If you're not getting this then... your cats are still there and working. 

Also when you checked the Oxygen Sensor and Oxygen Sensor Heater, was it only after flashing a tune? Flashing a map resets them, you need to drive for a while, maybe about 30 mins, before they'll show the status. 

 

Edit:

One more.. are the cars you've been comparing against sedans? The sedans actually have an extra resonator in the exhaust that makes it quieter than the coupe. 
https://www.e90post.com/forums/showthread.php?t=123467

Edited by Matth5
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On 5/1/2019 at 7:23 PM, Matth5 said:

Hmm I'd say that's either catless or something is done to the exhaust, if you can't see any signs of the PE mod. That doesn't sound like a PE mod/exhaust to me so I'd lean towards it being catless. 

"So on MHD the option is OEM/Catted DPs, and I have always had it checked. Did you mean that I should uncheck it and see what happens?"

With it checked it should still trigger the codes just like with stock. You should have a check engine light and some fault code(s) about emissions. If you're not getting this then... your cats are still there and working. 

Also when you checked the Oxygen Sensor and Oxygen Sensor Heater, was it only after flashing a tune? Flashing a map resets them, you need to drive for a while, maybe about 30 mins, before they'll show the status. 

 

Edit:

One more.. are the cars you've been comparing against sedans? The sedans actually have an extra resonator in the exhaust that makes it quieter than the coupe. 
https://www.e90post.com/forums/showthread.php?t=123467

So this is what I get from MHD after driving for about a week and 20km daily.

 

24CF7557-D2C3-4F93-954C-2C8CBADC3210.jpeg

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