[RTCalifornia]

Hi Folks,
just wanted to share a different method for the 2nd cat delete. This method removes the Catalytic core only and should pass the visual inspection especially for California SMOG tests. I was surprise how easy and clean it was.

Background:
The sound of my zcp exhaust is good but wanted it to be a bit louder while maintaining the ability to be quiet when needed. I bought a 2nd set of zcp exhaust from a member in this forum and experimented on it just in case I royally screw things up, I would still have my original to go back to.

The mod:
I notice from day 1 these catalytic were 2 halves welded together with a huge seam tab.

I started with a grinder and ground about 3mm off the seams on both sides. I then cut only the top half of the shell and the Ceramic core literally rolled right out. The core is held in by some heat insulation shield which came off easily too. It took about 3 hours to remove and Tig weld it all back together. Because I had only cut the top half, I did not have to re-align the tubes between the mid section to the flange pipe as everything was still held together. It was all too easy.

Here are some pictures of the process and the comparison between the modified and stock zcp. If you live in California and want to go with the 2nd cat delete, try this method and you shouldn't have to worry about the visual inspection.

The sound now is noticeably louder with the valves open when listening outside the car. BMW did too good of a job keeping the noise shielded when inside the car so the sound while driving is only a tad louder.

1st picture shows the cut revealing the ceramic core and insulation
2nd picture is the completed cuts
3rd the cats completely welded back.
4th close up of the original cat.
5th sizd by side zcp stock vs zcp catless core
6th car on lift