kimeran

I know this topic has been covered a million times, so apologies if its been asked.
I'm considering doing a decat on my P31 C63.
I don't plan on doing a tune or anything else.
Car is also under motorplan.

So my question is...
Which cats should I remove? Primary? Secondary? Both?
Should I hollow out the cats, or cut them out?
I'd like it to be louder, but not too noticeable that MB would be able to pick it up immediately.

Also, will I end up getting errors popping up? If so, what can I do about that?

Thanx a mill

Mark63

If you remove your primary cat you'll end up with a gas smell coming out of your exhaust and you'll be loud, the dealership will definitely notice.
Secondary cat won't give you that bad gas smell (from what I heard) but you'll still definitely hear the sound difference and the dealership will hear it too. Removing the cats will make your car loud.
If you remove both, good luck with your neighbors and the cops!

I had my primary cats removed and I added headers from MBH (great headers) and a straight pipe and my neighbors called cops on me. I deserved it because it was like 3am and I was just getting home.

I got a Check engine light after installing my headers and removing the cats and putting a straight pipe but I got a tune and had my mechanic install L spacers to by pass the O2 sensor and it went away.

akmatic63

no errors with secondary cat removal. Would recommend a X pipe to replace secondary cats and resonators if you don't plan on getting headers and tuning the car.