Catted downpipe experience

Edgar_FriendlyX3M · 12-01-2022, 09:40 PM

Hi all. What is your experience with the x3m/x4m and high flow catted downpipes? Mainly, any check engine lights or emissions issues when running a bootmod3 tune. I have a set of vrsf catted downpipes and have read some conflicting info on what I should expect.
Any input is appreciated!

dmanb2b · 12-02-2022, 11:40 AM

Not sure how Chicago is, but if you need O2 monitor readiness to be present, vrsf may not have good enough cats to help you avoid a CEL. Yes I know that a tune can suppress, but it won't help with readiness. You could run a spacer/defouler, but no guarantees. TBH, with some of the times people are running on the stock downpipes, I don't think they are all that restrictive, so not sure of the benefit going to another catted downpipe.

Edgar_FriendlyX3M · 12-02-2022, 12:35 PM

I'm not entirely sure either from an emissions standpoint on whether or not I'd pass. What do you mean when you say readiness?

itsrichierich · 12-02-2022, 01:07 PM

Honestly, it's a 50/50 when it comes to emissions with the high flow cats, so I always recommend catless.

Now, everyone's definition of "fume smell" differs but my wife and I both agreed it wasn't bad on my F30 335i.

Will need a flash/tune to get rid of CEL.

12-01-2022, 09:40 PM	#1
Edgar_FriendlyX3M Lieutenant 602 Rep 482 Posts Drives: 2020 BMW X3M Join Date: Feb 2022 Location: Chicago (city of the corrupt) iTrader: (0) Garage List 2020 BMW X3 M [10.00]	Catted downpipe experience Hi all. What is your experience with the x3m/x4m and high flow catted downpipes? Mainly, any check engine lights or emissions issues when running a bootmod3 tune. I have a set of vrsf catted downpipes and have read some conflicting info on what I should expect. Any input is appreciated!
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12-02-2022, 11:40 AM	#2
dmanb2b Banned 2123 Rep 3,368 Posts Drives: G07, F97, F30, E90, E46, E30 Join Date: Jul 2016 Location: NY iTrader: (5)	Not sure how Chicago is, but if you need O2 monitor readiness to be present, vrsf may not have good enough cats to help you avoid a CEL. Yes I know that a tune can suppress, but it won't help with readiness. You could run a spacer/defouler, but no guarantees. TBH, with some of the times people are running on the stock downpipes, I don't think they are all that restrictive, so not sure of the benefit going to another catted downpipe.
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12-02-2022, 12:35 PM	#3
Edgar_FriendlyX3M Lieutenant 602 Rep 482 Posts Drives: 2020 BMW X3M Join Date: Feb 2022 Location: Chicago (city of the corrupt) iTrader: (0) Garage List 2020 BMW X3 M [10.00]	I'm not entirely sure either from an emissions standpoint on whether or not I'd pass. What do you mean when you say readiness?
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12-02-2022, 01:07 PM	#4
itsrichierich Moto Lover 187 Rep 591 Posts Drives: '19 BMW S1000XR Join Date: Jun 2020 Location: San Diego, CA Instagram - @itsrichierich23 iTrader: (0)	Honestly, it's a 50/50 when it comes to emissions with the high flow cats, so I always recommend catless. Now, everyone's definition of "fume smell" differs but my wife and I both agreed it wasn't bad on my F30 335i. Will need a flash/tune to get rid of CEL.
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