tcsracing1

What is the deal with the cat on the 993 exhaust?

It appears bulky and old.
Who makes deletes?

If removed, what is required to keep the computer happy? Difference between early 1995 and 96-98?

What does it sound like with stock mufflers when removed? too loud?

What is a good muffler to use with the delete?

1990-964

I have cat bypass pipes I am no longer using. 95' Bischoff style. PM me if interested.

Eurotrio

I am using a B&B cat bypass on my 95'. Sounds great with RSR mufflers. Low end torque is improved and top and power as well. For the sound.......perfect. Loud when wanted and tame when desired.

1stgear

Fabspeed bypass here. I ran initially with stock mufflers and you get a little popcorn and grumble, but still very tame. I now run with Fister IIs and the car sounds like the gates to hell have opened. Very reasonable sound levels and no drone with the windows up. And with the windows down, tons of fun. Especially when backing into the garage.

Jay J

I have

DiegoR

When bypassing the CAT (or delete it) do you guys feel/smell stronger the emissions? I was/am debating my self if delete or not the CAT of mine but I didn't want to get the emissions odor arround while parking etc.

Eurotrio

DiegoR: With windows down you can't tell a difference until stopped and the wind blows the right direction. Windows up and not a difference.

Mark in Baltimore

You won't detect any smell, but everyone behind you will. I've gone on some Rennlist runs, and a few people said that they could not follow me due to the fumes.

I have the DACH, X-shaped, cat delete. Quality piece.

ilko

Cat delete stinks. You'll notice it immediately the first time you start the car in your garage.

Pags993

^ agreed. I always ask who runs without one when we do PCA fun runs up here and avoid them like the plague. A few years ago I felt like I was going to pass out running behind a cat delete C2S.

Bill Verburg

There is a huge difference between doing this on an OBD1 car and doing it on an OBD2 car.

To reiterate, US '95 and all normally aspirated RoW are OBD1
US '96 up and all turbo are OBD2

on an OBD1 car a cat by pass is simple, there are 2 styles, both cross the car one merges the 2 sides the other keeps them separate, the only advantage of the merge is it's slightly quieter, the separate style is a better performer, both are much lighter than the oe Cat. On these there is only 1 O sensor, oe it is placed in a central mixing chamber in the cat, w/ a bypass just place it in either side.

An OBD2 car has 2 pre and 2 post cat O sensors, the pre cat are no problem, just put one is each side of the bypass. The 2 post cat sensors are the issue, the DME has to have their signals, which are compared to the pre cat signals and a code is thrown if the cat is missing because there is no change in the exhaust gas composition. One possible solution is to mount the 2 post cat O sensors in clean air such as the engine compartment, keep them hooked up electrically and the comparison signal shows the cat to be doing a great job.

There is no doubt that a catalyzed exhaust is far sweeter smelling than a de catted one.

Spyder_Man

Not to derail the OP conversation but how about use of modern Sport Cats? Easy to install? Differences between OBD1 and OBD2? Any real performance gains or exhaust note changes?

As these cars age, failing OEM cats will become more frequent and I'm sure OEM replacements aren't cheap, nor as well designed as modern cats.

Falcondrivr

Shoot me an email or call me. My number is published in the front of the Suncoast PCA newsletter. I have the Fabspeed cat delete x-pipe. You can see/hear/fee/drive my car and decide for yourself.
I'm in Brazil until Friday night, but will be around this weekend. Don't wait untill after as my can may be sold this weekend...
Rick

race911

Somewhere around 130K the original on the 4S packed it in, CEL-wise. A guy here had a really low mileage one for about $250 shipped. Even though it's a no-no, who'll know OE v. OE.

tcsracing1

i am currently on business in canada ans away from tampa.
thanks however!