Idk if this is tech or general discussion
this is regarding gutting cats but first let me give disclaimers lolI don't notice the smell nor do others. I've gutted the last 2 c5s I had and the c4.
As on the others there wasn't much drone for meI won't do an x pipe at all and will never do headers.

Ok, what I've noticed is many people gut the rear 2 cats but what about the tiny ones by the manifold? If you gut those do you have to take off the manifold or can you unbolt them from the flange under them then let the catalyst fall?
When people gut the 2 rear IVE noticed it sounded better even when I did it to my last c5 but what about all 4?

I have a 98 a4 with flowmaster outlaw exhaust by the way
Why won't I do headers and all that? I'll explain. I can't afford it. I'm in disability with a terminal Illness and a single father. To me with my finances/price//tune/x pipe=gains...to me the juice isn't worth the squeeze for what I make
Also I must be the only person in the world that doesn't like the xpipe much. Yeah the xpipe quiets and smooths out the rumble motorboat sound but honestly I like it over the mellow smooth xpipe effect. I wish I can do so much but I. Constantly in the emergency room and just can't afford it.

So any input would be great.

 

I hope your health improves . I can't say much else , I have a flow master axle back system, and consider that a little loud for my tastes, but like the slightly improved efficiency. Some consider exhaust noise pleasant, I prefer music.

 

The cats aren't a restriction. Gutting them is kind of a silly move especially right now considering what they sell for.

 

I would do high flow cats. I tried it and it caused my car to run very rich and would get raw fuel smells and actually concerned me. I switched it back pretty quickly.

 

I'm highly considering that however I'd gut them. My last 2 c5s had gutted cats and I never had an issue with smell or anything but that is a big option I'm considering. Does brand really make that much if a differnce because I've seen some high flows that cost alot!

 

You're totally wasting your money if you gut a set of high flow cats. Also, brand doesn't matter at all if you're just going to gut whatever you get. If you're really hell bent on gutting them, just gut your OEM cats, and leave it at that. Once you gut them, the OEM cats, and high flow cats will both flow about the same since they have nothing left inside.

 

Very good point! I didn't think about that

 

I think brand does make a difference, I purchased the American Racing SS X pipe with the high flow cats attached already. Also remember that you can do some damage as well if you remove the cats unless you have a tune performed. Ive seen the computer dump extra fuel to cool cats that don't exist and cause the car to run so rich that the oil will smell like gas. I would imagine if that happens maybe you could flood the oil from the cylinders and cause early wear too.

 

Good to know! My only experience with it was on my 99frc I had I gutted them with zero issue or tune and with the Billy boat bullets it sounded like NASCAR. However I've never seen anyone gut the front tiny ones by the manifolds. What'll that do/sound like with all 4 gutted?

 

So I'm assuming these universals will work? Also if so then I can sell mine. Do my sensors plug into this or will I need to bypass that?

 

 

What does the number of "cell" mean? And can they just be clamped on?

 

The cell count refers to the density, or number of cells in a standard area, Lower cell count results in less flow restriction.

Can they be clamped on? Don’t know, but they look like they were intended to be welded on.

 

Common sense I figured it out. Catalyst amount. I'm assuming by the pic that it is a weld on. How do they sound? What mufflers r you running? Did you tune? I know that sounds stupid but I drive around 1200 miles a year so that's why I ask. Also does the lack of back pressure exist when doing this?

 

This info was provided to me in another thread, so I can’t answer all your questions. Still I have researched the subject and found there is some back pressure from the cats, but not much. If your installing headers, the pup cats will be eliminated anyway.

 

The OEM cats have a different inlet and outlet diameter. I think 3" in and 2.5" out. Also, the inlet and outlet are not in line. The out is offset to the center of the car by an inch or so.

Universal cats are definitely not a cut out the originals and clamp new in place kind of swap.

 

im glad you said this because I was just about to look into that

 

That is what I did, years ago. Just gutted the 2 rear ones, NOT the "pup" cats. Then I used O2 Sims in the harness until I finally had them tuned out.

 

What did it sound like? What exhaust did you have?