Catted Mid pipe project
 

Hi everyone,

I need your insights on a odd idea I just had.

What I want:
- To benefit from the extra power a catless header allows (think Ace header / Tuning Development UK with a tune) with an reasonable amount of exhaust smell

What I need:
- To still pass inspection (Europe - Belgium / they don't fuck around with CO emissions).
I can manage to get the exhaust pretty hot before passing inspection.

What I though of:
- Adding one or two 100/200 cell cats on the midpipe.
I believe the stock cat header is a 400-cell right?

Why?
Because it looks like the easiest way to relocate a cat.

My questions:
- Would adding those cat down the line get the aforementioned effects I'm looking for?

Thanks in advance for your inputs.

Just swap the OEM back in when inspections come around. It's what people doing in California and other strict emission states here.

You know there's a secondary cat in the front pipe already, right? Are you talking about adding one after that, or another in front of it in the front pipe?

Be wary that the center pipe section is recessed into the car's body, it's not like you have a ton of room to fit a wide cat in. They may penalize you anyway because the catalyzer is only effective when it's closer to the heat source.

Yes, but smell with catless is absurd, any cop will notice that you are catless...

That's what I used to do but this solution doesn't get rid of the smell.

I'm looking for something that could look OEM and therefore pass inspection, that gets rid of the smell and that allows me to mount a catless header (and benefit from the better exhaust scavenging and more aggressive tune).

I often read that the placement of the cat on the header is only to insure faster heat up process and that the stock cat is a 400-cell one.

Would adding one 200-cell or two 100-cell down the line achieve this?

If you omit the cat in the header and add a second cat to the mid pipe in addition to the one that is already there, I do not believe the second one would get hot enough to be effective. That is just a guess though. Only way to know is to try.

I guess that if header is coated & wrapped to retain heat inside more, then more of heat can be passed to cats in midpipe aswell, no?

Increased heat, increases NOx emissions. So as long as it is not knocking NOx out of range that may work. Would be nice if OP had access to a private shop with an exhaust gas analyzer. Only way to know for sure is to try.

If all you're worried about is smell, keep the stock front pipe, or get one with a high flow cat in it. Problem solved.

I've already run a catless header setup with the stock catback and the smell was already beyond what I can tolerate unfortunately.

If the cat is placed just a bit after the FP cap, then, it could get up to temp as well as the FP cat does, couldn't it?

It sounds like you should just keep the exhaust stock... and supercharge.

What front pipe though? There's two cats stock, one in the header and one in the front pipe. The catback is after the front pipe.


https://i1.wp.com/blog.modbargains.c...st-diagram.jpg

Don't worry, I know the exhaust like my pocket, ahah!
I mean, would adding a 100/200-cell cat after the second cat do the trick?

I don't care if the care smells when it warms up. As long as, when it's warm, the smell is gone, then mission accomplished.

But would I benefit from the added performance of a catless header? Just by "moving" the first cat down the line and swapping it for a sportier one?

Supercharging... I would love that! But hey, this is Belgium...
Change your rims and you won't pass inspection. That's half true though.