What is a catless down pipe?

I thought the cat part was AFTER the downpipe?

I thought the downpipe was first and then the exhaust, and the cat part was on the exhaust part. Is that wrong?

 

The cat is on the downpipe

Good pic to learn the exhaust system



Heres a good pic of each type of downpipe. Bottom stock, middle catless aftermarket, top aftermarket w/ cat (maxxfab)



Pics from http://www.maxxfab.com/

 

OMG, Andy! That is what I've been needing! I needed a picture of it!
Thanks! I'm going to be studying up on it now.

 

is it street legal to run it without the cat?

 

It's against Federal law to remove or replace the cat under most circumstances. This page talks about the regulations, http://www.car-sound.com/catalog/notice.aspx


Basically it depends on where you live and the emissions inspection you have to go through. There are many places in the US it seems that don't have very strict emissions guidlines, I guess due to them not being overcrowded and smoggy like the rest of the country. So a lot of people can get away running no cat without ever having a problem.


With that being said, a lot of things are illegal that people do anyways. Personally, I plan to go with a catless downpipe with cutout and will just swap the stocker back in when it comes time for emissions which isn't for four years for me. So it's not a big deal. There can be pretty hefty fines if you get caught and thats the whole key to it, not to get caught lol. In CA the CHP are trained to look for things like that along with any aftermarket parts. Street racing/reckless driving increases your chances of getting caught for such a thing a ton. I don't believe for the most part you'll ever get pulled over just driving down the street normally because they think you don't have a cat.

But these guys that sell the catless downpipes do put warnings that they're for offroad use only. You use them at your own risk.

 

Been studying the exhaust pic and it seems to me that there are just two parts. The downpipe and the exhaust. What confused the hell out of me with all this was it being called a "catback" exhaust. That sounds to me like it means that the exhaust includes the cat. But now it is starting to make sense. It's FROM the cat and then back. Makes a lot more sense to me now. The only question I have regarding the exhaust now is, does that 02 sensor pipe need to be changed, too? And what is that piece sticking out of the downpipe....off the bottom of it?

 

You don't have to replace the 02 housing... Just like you don't have to change the downpipe you could just go catback it just depends how far you want to go. Research and see if the gains are worth it to you. I haven't read much on it so I don't know much about it.


Not sure exactly what you're refering that's sticking out of the downpipe...

 

I have researched it, and from what I have read, the downpipe is very constricting. As a matter of fact, IF I UNDERSTAND THIS RIGHT, the downpipe would probably be the most beneficial thing to change. It is getting a lot clearer to me. That picture you sent really did help. Good to know the 02 pipe doesn't need to be changed.

 

But changing the O2 pipe will help. If you plan to keep the stock turbo, and are doing a 3" downpipe, why not just do the extra 110$ for a 3" o2 pipe while you are in there anyway? That will give you a true 3" system with smooth flow. The stock o2 pipe is pretty restrictive.

I would have done the o2, but I plan on going to a bigger turbo, so it would be a waste and redundant, since it wouldn't mate up to the larger turbo.

 

Thanks, PHR.

I'm guessing that when you change out the 02 and everything, then that must be the turboback. FROM the turbo back.

Got it!