Converting SCR into a muffler for off road (emissions delete) 335D

Tomnavigator · 12-05-2022, 02:15 PM

I never heard of anyone else doing this so I decided to make a post on making the SCR into a muffler. The following is only for those who are planning to delete the emissions control equipment of their 335D for off road use and want the quietest car they can get.
A friend of my son who lives out in west Texas owns a 335D he was converting to an off road use only vehicle to be used for hunting (now I have heard everything). I was asked to help with the welding needed on his exhaust system. He told me he was performing an emissions delete on his 335D to be used off road only for deer hunting.
He brought the exhaust system over to my house for me to weld the covers back on the DPF and SCR after he had removed the catalyst from each. He removed the DPF and the DPF particulate filter portion of the exhaust was removed leaving the DOC in place. All unused ports in the DPF were welded up.
He removed the SCR cover and removed reduction catalyst from the SCR. He told me he wanted the car to be as quiet as possible since he wanted to use it for deer hunting. I told him I had a stainless steel plate and we could cut to make baffles for the SCR to convert it into a muffler. Here is what we ended up doing.
Five stainless steel baffle plates were cut for the SCR. Three of the baffle plates were cut with holes at each end to force the exhaust gas to divide and go through the holes at each end of the baffle plates. The other two baffle plates were cut with one hole in the middle to force the exhaust gas back to the center of the SCR. The baffles were installed in the order of two hole baffle, one hole baffle, two hole baffle, one hole baffle, and two hole baffle (see pictures). The SCR cover was then reinstalled in five pieces and welded back into place. The cover was cut into five pieces so it could be welded up to seal the baffle plates. See the picture with one cover piece ready to be welded back in. I was told later that his car exhaust sounded completely stock with no noticeable increase in exhaust noise.

who is this noob · 12-10-2022, 01:05 PM

Tom, thanks for sharing!

Got a video demonstrating how this sounds?

A before / after dyno comparison would be great. But it sounds like they’re less interested in performance and more interested in wildlife.

lnxguy · 12-10-2022, 01:29 PM

If you're interested in wildlife you wouldn't touch the SCR lol.

Tomnavigator · 12-11-2022, 12:18 AM

I don't know how meaningful a sound clip will be since you are only talking about volume. My son's friend told my son that he can not hear the turbocharger spool up at all when he gives it throttle unless he is standing behind the car and then only slightly. This is not my car so I can only ask to see if he will record it. I will ask my son to contact him. It will be a while before I can post it here. I don't know when my son will see him.

Tomnavigator · 12-11-2022, 08:41 PM

I contacted my son about recording the exhaust of friend's 335D. My son told me his friend sold the car.

12-05-2022, 02:15 PM	#1
Tomnavigator Private First Class 91 Rep 195 Posts Drives: 2010 335D, V-10 Touareg Diesel Join Date: Mar 2015 Location: Southwest Louisiana iTrader: (0)	Converting SCR into a muffler for off road (emissions delete) 335D I never heard of anyone else doing this so I decided to make a post on making the SCR into a muffler. The following is only for those who are planning to delete the emissions control equipment of their 335D for off road use and want the quietest car they can get. A friend of my son who lives out in west Texas owns a 335D he was converting to an off road use only vehicle to be used for hunting (now I have heard everything). I was asked to help with the welding needed on his exhaust system. He told me he was performing an emissions delete on his 335D to be used off road only for deer hunting. He brought the exhaust system over to my house for me to weld the covers back on the DPF and SCR after he had removed the catalyst from each. He removed the DPF and the DPF particulate filter portion of the exhaust was removed leaving the DOC in place. All unused ports in the DPF were welded up. He removed the SCR cover and removed reduction catalyst from the SCR. He told me he wanted the car to be as quiet as possible since he wanted to use it for deer hunting. I told him I had a stainless steel plate and we could cut to make baffles for the SCR to convert it into a muffler. Here is what we ended up doing. Five stainless steel baffle plates were cut for the SCR. Three of the baffle plates were cut with holes at each end to force the exhaust gas to divide and go through the holes at each end of the baffle plates. The other two baffle plates were cut with one hole in the middle to force the exhaust gas back to the center of the SCR. The baffles were installed in the order of two hole baffle, one hole baffle, two hole baffle, one hole baffle, and two hole baffle (see pictures). The SCR cover was then reinstalled in five pieces and welded back into place. The cover was cut into five pieces so it could be welded up to seal the baffle plates. See the picture with one cover piece ready to be welded back in. I was told later that his car exhaust sounded completely stock with no noticeable increase in exhaust noise. Attached Images Last edited by Tomnavigator; 12-05-2022 at 03:07 PM.. Reason: pictures
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12-10-2022, 01:05 PM	#2
who is this noob who is this noob 93 Rep 229 Posts Drives: from Spartanburg Join Date: Jul 2012 Location: The Evergreen State iTrader: (0)	Tom, thanks for sharing! Got a video demonstrating how this sounds? A before / after dyno comparison would be great. But it sounds like they’re less interested in performance and more interested in wildlife.
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12-10-2022, 01:29 PM	#3
lnxguy Colonel 536 Rep 2,061 Posts Drives: 2018 540i xDrive. Join Date: Jun 2016 Location: Barrie iTrader: (1)	If you're interested in wildlife you wouldn't touch the SCR lol. __________________ '09 335D '18 540i xDrive
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12-11-2022, 12:18 AM	#4
Tomnavigator Private First Class 91 Rep 195 Posts Drives: 2010 335D, V-10 Touareg Diesel Join Date: Mar 2015 Location: Southwest Louisiana iTrader: (0)	I don't know how meaningful a sound clip will be since you are only talking about volume. My son's friend told my son that he can not hear the turbocharger spool up at all when he gives it throttle unless he is standing behind the car and then only slightly. This is not my car so I can only ask to see if he will record it. I will ask my son to contact him. It will be a while before I can post it here. I don't know when my son will see him.
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12-11-2022, 08:41 PM	#5
Tomnavigator Private First Class 91 Rep 195 Posts Drives: 2010 335D, V-10 Touareg Diesel Join Date: Mar 2015 Location: Southwest Louisiana iTrader: (0)	I contacted my son about recording the exhaust of friend's 335D. My son told me his friend sold the car.
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