Cat Converter question

[Ken Potter]

HI guys,
Considering gutting out the CAT. I have heard some say ( on other cars) you want the backpresure the Cat gives you. This back presure they talk about makes no sence to me but im just me. Is there an advantage in cutting the CAT for performance? Forget passing inspection topic please.
Next question. What header brand sells you a header that will directly fit up to the existing exhaust past the CAT so as to totaly delete the cat. Some companys I have talked to state modifications my be needed but dont tell you what? Im just wanting to replace that sick stock header and also delete the cat and directly bolt up to the rest of the exhaust. I dont need stainless steal and would rather not go with it either. I also dont want to have to worry about the header hitting the rad or rad fan housing. Any suggestions on brands guys?

[zxtuner98]

gutting the cat is nice if you wanna free some flow, but keep it stock before that, or run a shorty header. Some different header's that delete the cat are OBX, Hotshot, Kamikaze, Gude.

[NRRACINGCEO]

tell ya what, I have the Kami with no CAT and all exhuast work done and a SCT tune and she scream like a banshe above 4200 man, Do it the power is nasty up high with the KAMI. I did the Kami for high RPM power. Also i put brand new o2 sensor and a new CSP sensor in the car at the same time, it loved that.

[Beodude123]

If you are going to go full length (deleting the cat altogether), go with the Kamikaze. It's probably the best header out there.

I'm not going to say don't listen to the folks that talk about back pressure, but don't take much faith in their exhaust knowledge. Back pressure is bad, plain and simple. It's bad to have any sort of restriction in the exhaust.

[iceracer]

Beoude is right on the back pressure. I'm surprised there a still people saying you need back pressure. Nonsense.

[mechtech]

Backpressure is NEVER good in an exhaust.
There is some in various degrees, but it impedes the purging of the exhaust, and the filling of the cylinder.
Well, OK... some 2 stroke bikes have negative pressure from the expansion chamber/pipe, and suck too much fuel. But this is a carbureted old school thing on certain 2 stroke race vehicles.
If your cat is not puked, I'd leave it. Much better for noise, and no harm to the power or economy unless maybe at full throttle, which is 1-2% of your driving. There is some restriction then, but not as bad as many believe with modern honeycomb [and properly sized] cats.

[Beodude123]

People get back pressure and airflow mixed up. They think that if you go with too large a pipe, you lose "backpressure", which makes less power to the wheels. The reality of it is that you don't have enough air to fill the tube. Once it does get filled, you will have power all over the place though.

One instance of this would be getting a 3" exhaust for a stock ATX. You would never be able to fill it really well, and it would rob you of power. Now, on a car with a turbo, that 3" is going to be just right.

[evildick]

i just gutted my cat and made the Mil Eliminators and it works freeing up back pressure .TIME SAVING TIP! use a roto hamer to clean out the cat !:rocknana:

[mechtech]

How about the noise level?

[OGreaTFuzzY1]

cut the cat and send to meh!

~Fuzzy

[Beodude123]

To be honest, if you are going to go through all that work to get the manifold off, you might as well wait and replace it.

I don't know how much a gutted cat with give you power-wise, but I would consider the time / potential gain ratio pretty bad.

[zxtuner98]

To be honest, if you are going to go through all that work to get the manifold off, you might as well wait and replace it.

I don't know how much a gutted cat with give you power-wise, but I would consider the time / potential gain ratio pretty bad.

QFT. try breaking the manifold/cat bolts loose. 10 years of heat cycling FTL lol. I was able to drop mine through the bottom of the car. A/c is gone tho that helped a bit. Just wait and put a header on.

[Beodude123]

Yeah dude, it is a pain in the ass. With AC there, it can't be done. I had to break the manifold apart. Those bolts are mean. Rusted and heated. They are pretty much welded on.

[zxtuner98]

i broke alot of extensions and swivels before i said fuck it and got the hacksaw out and started cutting lines haha.

[JonsZX2SR]

If you are going to delete the cat anyway, try to find a SVT Focus 4-2-1 header and have a pipe fabricated to connect the header outlet to the ZX2 catback exhaust.