layzie12g

I ordered a set of MBH long tubes for my E63. I have a question regarding secondary cats. With my 55's I have always ran 200 cell Vibrant race cats in place of the secondary cats.

Today I saw an E55 guy ran his long tubes to the secondary cats. This was a high 10 second car on sticky tires. I assumed they were a 600-800 cell cat. I know they are a different material then the primary cats internally. Any one have any input on this? I wouldn't mind saving a couple hundred bucks and the time welding in the Vibrant cats if the stock secondaries are not as restrictive as I'm thinking they are. Going catless is not an option. I can't stand the smell.

Any feedback is appreciated.

kb24forlife24

Mods please move to E63 forum

layzie12g

Why would you say that? We all have the same 156 engine. In theory there would be a lot more N/A tuning going on here then in the E55/E63 part of the forum. In the 211 part of the forum its 90% supercharged 5.5 guys. All of which share a lot of knowledge, but I'm trying to get some information from people who have made power with the 6.2.

Really though... That would be like me asking them to move you and your CLK with quad exhaust to the CLK with part of the forum. That is the first douche thing I have ever seen anyone post in response to any of my threads on this forum.

BLKROKT

I think he said that because your question is a little unusual in its phrasing, and doesn't make sense - perhaps he thought it was E-specific. Most of us run LTH with primary cats, and delete the secondary cats. Don't need them, they are not being monitored, and the primaries do a good job. I don't know why you would want to run LTH through *only* secondary cats? Then you mention that you don't want to go catless... but what about the primaries... what are you talking about exactly. Have you looked under your car to get a sense of what's going on there?

layzie12g

I'm a Benz mechanic for a living. I do understand whats going on, and I tried to rephrase my first post because it was not easy to understand what I was saying after re-reading it. I've assembled (short block) and tuned a bunch of 700+ horsepower Mitsubishis so I'd like to think I can bring some knowledge to the table.

My "through" I meant the exhaust flow from the headers are being ran through a restrictive stock catalyst. I'm basically asking if anyone has any numbers with stock secondaries vs aftermarket cats vs catless. I know catless with all ways make more power. I gutted the cats on my CL. Both the primary and secondary catalyst materials where DENSE.

If I'm going to be shorting myself 10 horsepower between 200 cell cats and the O.E.M. secondaries I won't mind buying race cats and welding them in. I think your saying you run aftermarket cats after the collector as a primary cat so the 02 sensors reading a functioning cat.

kb24forlife24

OP I didn't mean to offend you; I just thought you accidentally posted in the C63 forum.

Mort

I am running MBH LTH with catted (200 cell I believe) mids and an x-pipe all supplied by Mike. It is a direct bolt in system with no welding required. This is a beautiful well designed system and what I would recommend. I know this may not meet your needs or preference so just saying.

Sorry no HP numbers so I cannot help with that. I did read a post ages ago about a guy from California that had Cali legal cats installed in the MBH system and it cost him 20 whp. I don't know how many cell the cats were but maybe Mike might remember. That might give you a reference for stock secondaries vs 200 cell cats.

layzie12g

I didn't mean to snap on ya. I was in a bad mood last night. Thanks for the info. Cali legal cats were probably a ceramic cat. I'm really leaning towards the Vibrants at this point.

I am Jeff

If you're concerned about gas smell and don't mind losing a few rwhp (15-20), just order 200 cell cats. You will place them after the primary collectors .

Your exhaust will only smell of gas upon initial startup. It will go away once the engine is warmed up. I currently run the ARH headers with 200 cell metallic cats and xpipe.

MJ50

moved to W211 AMG forum...