Removal of the secondary cat on M2.....

widetyres · 06-14-2019, 03:21 PM

...but the M2 doesn't have 2nd cats I hear you say!....

...and that was my belief, however, I've been educated through a Facebook post that the M2 does have a secondary cat that can be removed!

Within the OEM downpipe, there are two separate cat monoliths, one after the other with a void in-between. Only the first cat is monitored, and this can be clearly seen by looking at any pic of an OEM cat and the lambda placement.

As a result, you can smash out the un-monitored cat. The result will be no CEL, just a bit more exhaust noise and maybe a bit more power.

Has anyone on here done this? I haven't seen any threads about this before.

Anyone know of of any videos showing this?

Cheers.

cecaa850 · 06-14-2019, 04:47 PM

You'd have to pull the pipe to do it correctly otherwise you'd stop up your muffler with pieces of catalyst.

3LiterBeater · 03-15-2021, 05:04 PM

Wanted to bump this. Interesting way to eliminate the "pre" cat element which I'd assume is the most restricting.

Has anyone done this?

06-14-2019, 03:21 PM	#1
widetyres Lieutenant 279 Rep 488 Posts Drives: M3 E92 DCT, 2012 Join Date: Oct 2018 Location: UK iTrader: (0)	Removal of the secondary cat on M2..... ...but the M2 doesn't have 2nd cats I hear you say!.... ...and that was my belief, however, I've been educated through a Facebook post that the M2 does have a secondary cat that can be removed! Within the OEM downpipe, there are two separate cat monoliths, one after the other with a void in-between. Only the first cat is monitored, and this can be clearly seen by looking at any pic of an OEM cat and the lambda placement. As a result, you can smash out the un-monitored cat. The result will be no CEL, just a bit more exhaust noise and maybe a bit more power. Has anyone on here done this? I haven't seen any threads about this before. Anyone know of of any videos showing this? Cheers.
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06-14-2019, 04:47 PM	#2
cecaa850 Captain 259 Rep 699 Posts Drives: 2018 M2 Join Date: May 2018 Location: South East TX. iTrader: (0)	You'd have to pull the pipe to do it correctly otherwise you'd stop up your muffler with pieces of catalyst.
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03-15-2021, 05:04 PM	#3
3LiterBeater Second Lieutenant 130 Rep 221 Posts Drives: BMW M2, Porsche 944 Turbo Join Date: Dec 2020 Location: Maryland iTrader: (0)	Wanted to bump this. Interesting way to eliminate the "pre" cat element which I'd assume is the most restricting. Has anyone done this?
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