Stock downpipe catalyst removal

[m5james]

Get a flash tune from Halim/HCP to prevent the CEL you'll get for no cats, then that'll REALLY wake up the car.

[apsuard]

Originally Posted by ice7

Thanks for the feedback. Been debating about doing this since I was afraid of stock DPs wouldn't get smooth flow with the catalyst removed due to the change of diameters through the piping. I do have a E-Race as well and bet it sounds intoxicating

My car pulls like a freight train now and sound is epic. Pissed at myself I didn't do this last year.

[ice7]

Originally Posted by apsuard

My car pulls like a freight train now and sound is epic. Pissed at myself I didn't do this last year.

Nice, what tune do you have?

[lporschef10m5]

Originally Posted by KaWi

I have done the same with my M5 Katalysts but the power on the Dyno was 30Hp less down to 700HP. After this I put 400 cells inside and I get 30Hp plus to 760HP. I think they need a bit pressure after the twinchargers.

That's interesting

[Max Payne]

Originally Posted by KaWi

I have done the same with my M5 Katalysts but the power on the Dyno was 30Hp less down to 700HP. After this I put 400 cells inside and I get 30Hp plus to 760HP. I think they need a bit pressure after the twinchargers.

That is very interesting to read. I‘d like to do the same thing on mine. Can you give me some advice on how to do it - like which diameter catalytic converters did you use, what material other than a welder and a catalytic converter do I need?
Thanks in advance

[Info@mad-us.com]

I feel like you can sell Stock cats and get big money for them easy.


Our downpipes have perfect fitment and lifetime warranty for under $300.

https://mad-us.com/mad-bmw-f10-m5-downpipes/