Cat by-pass pipe For 993

HI! i need info on changing the original catalytic to fabspeed catalytic converter bypass pipes. by the way my 993 is a C2. thanks

[Don Plumley]

Relatively easy. Disconnect the O2 sensors (1 if 95, 4 if 96+). Use an open end wrench or O2 socket if you have one. Remove the tail pipes, disconnect the cat from the muffler. Remove the straps that hold the cat. You might need to soak the various nuts in PB Blaster or use Heat.

Installation is the reverse of the removal - if you have an OBDII car (96+), you'll need to attach the post-cat O2 sensors to the car - ground the sensors and hang in the engine compartment or under the car.

[herman maire]

Does this mean you pretty much delete the cat?Will it still pass smog?

Thanks

[Don Plumley]

Originally Posted by herman maire

Does this mean you pretty much delete the cat?Will it still pass smog?

Thanks

Yes. No.

Removes weight aft of the wheels (good), removes heat from the engine compartment (good). Sounds amazing (good). Not so great for the air (bad).

I run mine with Cat Bypass on the track.

[herman maire]

Originally Posted by Don Plumley

Yes. No.

Removes weight aft of the wheels (good), removes heat from the engine compartment (good). Sounds amazing (good). Not so great for the air (bad).

I run mine with Cat Bypass on the track.

Thanks Don,

I would really like to delete my cat for all the reasons you mentioned but I cant help but feel guilty for not doing my little part for the air . Nuts huh ?

[Bill Verburg]

Even w/o the cat and consiering the relatively low milage we put on these cars I don't feel too guilty about it.

Your lawn mower probably pollutes more over the course of the year.

[Gventure]

Originally Posted by herman maire

Thanks Don,

I would really like to delete my cat for all the reasons you mentioned but I cant help but feel guilty for not doing my little part for the air . Nuts huh ?

But, if your current CAT has 400 cells per inch and you replace the CAT with a sport CAT with 100 cells per inch you'll get better performance w/o sacrificing the environment with a CAT bypass. If you do that then get rid of the secondary muffler (at least you can on a 964) , you'll save weight and be surprised how nice it sounds.


G

[North Coast Cab]

The change sounds simple, but the heat shield on top of the mufflers / cat can be a major PITA.
I had Fabspeed Supercups with stock cat and just went to Fabspeed cat bypass and stock mufflers. Seems to perform about the same, butmuch quieter. Just took a lot longer than I had anticipated.

[993inNC]

Originally Posted by Gventure

But, if your current CAT has 400 cells per inch and you replace the CAT with a sport CAT with 100 cells per inch you'll get better performance w/o sacrificing the environment with a CAT bypass. If you do that then get rid of the secondary muffler (at least you can on a 964) , you'll save weight and be surprised how nice it sounds.


G

Better be careful, 100 cell cats probably won't pass emissions testing (if done by sniff).

[Bad Bob]

Can the cat bypass pipes be run with one O2 sensor on a '95-993 or is the O2 sensor to be removed completely?

[993inNC]

a 95 is run with its one O2 since it's obd1. obd2 cars run the 2 pre cats o2's only.

[indra gunawan]

I ever run a cat bypass pipes on a 1995 993C2 which has 1 O2 sensor , anybody knows why it smoke when i downshift at high speed, or when i pull the gas at highspeed and backfired a lot.
The car had been scanned by PST 2 after that, but nothing wrong.
So i went back to use the stock catalytic converter, everything was going fine, no smoke at all.
Btw the engine only use a K&N air filter and a Broquet Fuel catalyst, other than that was stock.