905legend

Hey,

Anyone running high flow cats on their M156...I've got a ML63 and the cat's have gone bad..figured this forum gets more action.

Curious if anyone has high-flow cats and had issues with passing emissions test or having codes pop up or issues with the readiness monitors.

let me know

thanks

ExtremisTy

Disclaimer: I live in California, so I'm sure our emissions regulations are different. Apologies if my post is irrelevant.

Am I correct in assuming you're talking about primaries? Removing secondary cats should not have a significant effect on emissions. Changing the primary would depend on the number of cells. Generally more cells = cleaner emissions = less chance of failing. That said, it is really hard to know whether your specific HFC's will pass until you actually test. Also, I'd be sure to check your emissions regulations. Where I live, they also do a visual and will fail your car if they can tell you've modified the emissions components at all. Most California drivers with cars with headers or cat deletes just pay someone to get their car "passed".

saint13

Can't speak for Ontario emissions but I have a set of 200 cell cats after my MHP headers and am quite happy with them. If you end up going headers the high flow cats really help cut down on smell while sitting at stoplights and reduced noise a bit, which is great for a DD.

For what its worth, I passed California OBDII emissions no problem with my Eurocharged V5 tune and MHP headers and the cats. Have not had to pass visual though.

905legend

emissions here in Toronto, Ontario just look for no engine codes and the readiness monitors to be good. You are allowed one monitor to not be ready though.....I don't want to put high flow cats and it still throws a code.....It's just kind of hard to find a set of used ML63 cat's or going to have to bite the built and buy new.

ML63 only has a primary cat off the manifold doesn't have two sets like the c63. Just worried about it tripping a code ...

saint13

Are you open to tuning it? Eurocharged tune will let you pass OBDII emissions no problem. Then could replace the bad cats with whatever you prefer from the various levels of high flow cats or stainless straight pipes depending on your noise/smell tolerance.

I'm seeing ML63 primary cats at $1200+ per side which seems insane to me.

905legend

the car has a code now due to the failing cat...I'm looking at options to replace them ..

Vladds

I think 200 CPSI are sold as compliant for all states and that 100 CPSI are not sold for CA.
I had on my Subaru a 200 CPSI that passed in NY but when I looked at it next to a 100, looked a lot like the 100.

With this said, to take full advantage, you would need a tune, because the high flow can be metal substrate construction and those allow for higher EGTs. So the mix may be able to be leaned out a bit, the EGT don't have to be cooled with a rich mix.

Mikegpr03

I can add to this: If you solely have just 1 pair of cats I would run a set of 200cel units metal core. Reason being is that the smell of gas is gonna drive you nuts if your a picky guy. The minute you lower the window is gonna be 78 chevy camaro smell ( disclaimer: I love Chevy people they are fine folks ). Now if you go e85 run no cats ( assuming track of Mexico roads ) all day.