Anyone retro fit cats on stock rear section?

[M3ryder55]

For the longest time I?ve hesitated against DPs mainly due to CEL headaches without a tune and having my secondary cats deleted with my AA midpipe.

I was thinking about throwing my stock rear section back on with my AA mid and retro fitting some after market cats back there before putting on the DPs. Was curious if anyone has done this if possible? Any sound drawbacks? Waste? I just want something to kill the smell or help a little.

Thanks

[M-terkait]

Not sure, if they will even heat up to work as intended if placed in the rear.
that's why its placed right after turbos.

[ljzimm]

Plus your primary oxygen sensors are still going to be calculating poor efficiency if the cats aren't before them. You'd just be adding restriction to the system in an area that won't get hot enough to even help with your concern of smell.

[Bashar368]

I think what he is trying to do is use an aftermarket hi-flo catalytic converter to filter out the cat-less smell. I did this with my E46 M because the S54 like the S55 has a catalytic converter attached to the header is totally acts like a bottle neck.

A lot of people went cat-less and install the CSL M3 section 2 which had a cat.

[terahertz]

Is it just me or should he just buy HFC downpipes lol

[aBMWfan]

Originally Posted by terahertz

Is it just me or should he just buy HFC downpipes lol

+1

[M3ryder55]

Originally Posted by BenM4Dominate

+1

2500 seems steep for DPs with hi flow cats lol that?s why I asked.