How to delete the Catalytic Converter

[Tidybuoy]

My neighbor told me that the best sounding 944 he's heard was with stock exhaust and the catalytic converter removed. I'm sure there are opinions about the muffler but at this point I am going to stick with stock and just try the cat-delete.

I thought I would try this out and I'm wondering what is a good source for the cat-delete pipe. I'm assuming I can just unbolt the old and replace with a straight pipe (I haven't really looke under there lately but I assume it bolts into place).

Anyone who's done this, will this have any effect on how the engine runs - of course, I will replace for my emissions inspections.

Vern

[KY944S]

Last I looked it was welded in place. I think the best route would be to cut the old one out and bolt in a high flow cat. Legal yet better.

[robs944]

I 'm pretty sure that the cat is welded to the down pipe from the exhaust manifold, but it connects to the muffler section with a 3 bolt flange.

Never done it but I have heard of people doing this, also just "gutting" the existing cat. I don't know how your welding skills are but most folks just take it to a competent muffler shop to have one made up.

[blk924s]

The exhaust manifolts bolt to the first section of exhaust pipe (with the 02 sensor, test pipe bung, and cat), which bolts to the rear section with the muffler. I'm going to take a used first section, cut the cat out, weld in a piece of pipe, and install that in place of mine. Then if I need to swap in the cat, it will be easy.

[74goldtarga]

I like blks response, the cats are valuable, especially for resale to a state with emissions testing. Cutting yours out would make it worthless.

[mr. dude]

It's actually pretty easy to cut the cat out and weld in a straight pipe. I love Michigan, no emissions laws here!

[bholmes]

I just punched the guts outta mine. I think it sounds better, it really sounds pretty good. Some people think it makes more resoance in the cabin when you do this. I'd have to say it has just a bit more, but not enough to be anoying in my opinon. Ideally you could put a perforated core glass pack in place of the cat and weld the converter shield around it and then it would act as a low restriction premuffler/resonator/dummy cat. That is what I have planned some day for my car. So that's my two cents worth. I also think that it seemed to run a little better and rev a little freer. It seemed to take care of a flat spot up top.

[blown 944]

personally I liked the sound of the cat w/o muffler better when I did mine. Here is what it sounds like w/o cat and with original muffler.

http://www.youtube.com/watch?v=gYvr3k5kkmM&mode=related&search=

this one is the best representation of what it will sound like w/o cat. Not my best run

[bholmes]

Sounds pretty good. Did you gut your muffler similar to what Speedy did or did you just put a piece of straight pipe on it?

[bholmes]

There's how to gut a muffler! Compliments of Speedy.

My exhaust project. W/ cool pics!

[legion]

I used a sharpened three-foot piece of rebar, a sledge hammer, and a shop vac.

[924 driver]

I have read some about this. Don't gut the cat you can potentially lose power by doing this. You would only gain power if you had a cat that was clogged. I have read that when you gut the cat it will create turbulence. Either delete the cat all together or get a high flow cat.

[legion]

Not having it helps the spool-up on a turbo.

[Blondie]

I did a cat-delete 3 weeks ago...switched over to a stock muffler. Sounds easily 10x better than a beefier muffler+cat...

Not so much a 'VRROOM' anymore....now its more of a 'VRRRROOOWWWW' lol

[flash968]

yes, on a normally aspirated engine you can lose torque - you might pick up a pony or two up top though

the bigger issue is what it does to the mixture - removing it changes the back pressure, and consequently the reading the O2 sensor gets - this can be damaging

[Brando]

Get one of Russell Berry's chips, remove the CAT and/or replace it with a glasspack. Go with a turbo muffler. Sounds mean, not ricey.

[Marcone]

I removed most of the cat with a stick ... i used the garden hose to get the rest...

But in all seriousness....

its pretty easy to remove the cat... i did so on my Beemer and had straight pipes put in... got bloody loud tho... but that was a six with dual exhaust.

Sounds very mean tho.... you can also get resonators that look like cats, theyre essentially just a straight pipe that has a bulge in it.. holds a little pressure due to their design on the inside which can help the torque loss you may incur..but also gives a high end power gain...

[ilikemy944]

I gutted my cat.
I stopped driving it because it sounded that bad.
I replaced it with a straight pipe, much better.

[porsche4life]

where could i get my hands on one of these resonators and how much would it cost???

[Marcone]

Umm..
not too sure in the states. ... but in canada i got a resonator for like 59 dollars at a local muffler shop. they installed it and everything for another 50.

Lots of shops make them. just have to find the little shops that do

basically the inside of it looks like a cheese grater, so you can recognize one if you see it.

Hope that helps a little