Well it seems like you have already decided the cat isn't really your problem. Replace it if it has been killed, but yes you must figure out your spark or fueling problem or you will just destroy the next one.

Did you test the new fuel pump/filter/regulator and maybe the fuel tank vent vavle?

It might not be easy but getting a pressur gauge on the fuel rail and monitor it under load where it fails. Stationary reving is not like under load. Ideally you could do it on a dyno.

Check it out, https://www.youtube.com/watch?v=mLIJ...&feature=share
That is the change you gain by removing the cat and putting straight pipes, turning the check engine is a trick one though i have done it cost was 250$ (im based in Ukraine).

Cheers!

I wonder what the my corsa exhaust would sound like on there. To me the above vids too high pitched for what I would want in that situation.

I'd want something deeper sounding like this.

https://www.youtube.com/watch?v=nwfoRxJXhe4

It should sound something like this https://youtu.be/8YKP5pDYOfg since we have the same engine on the m5 e36 4.4v8

Ok THAT sounds good :)

Couldn’t agree less!
Thats a sound to treat heart diseases (doctor jokes intended):bustingup

Well one good thing about a well done straight pipe exhaust. They last.

This one was installed 48 years ago. No video of it but I did record it with my cell phone a few years ago. Need to do a youtube of it one day.

http://crowz.narmir.com/falcon/falcon.wav

Mate gotta say that sounds like a mercs G-wagon, which sounds lovely.
Im astonished to know that after 48 years that car still spread horror.

Cheers!