cat or no cat that's the question

[Garo156]

I would like to know if anyone had removed the cat of of their car and left the stock muffler. I am wondering about the sound. I have an 83 n/a and would like a deeper tone but not poppy or raspy like a ricer car. The 928 sounds great but I know that is a v-8 and I know I am short 4 cylinders for that particular sound. I just want it to sound not so much louder but mwer muscular. Any ideas would be helpful.

[Gawernator]

My car had a straight pipe on before I welded the cat back on. Didn't make a huge difference in sound. Slightly louder, more gurgly I guess, however the stock exhaust setup really does sound good.

[ckelly78z]

My 83 N/A had no cat and a turbo muffler at the back. I think the muffler might have been going bad because it was annoyingly loud and raspy while accelerating but OK while maintaining speeds.

My current 85.5 N/A has the cat still in it with a new Magnaflo catback system and it sounds great.....just a small bit louder than bone stock and not raspy at all.

[ernie9944]

My ex 83-944 had a Honda S/S cat stock muffler with a 4" exhaust tip,talk about a sweet sound.Little mod was require on the cat to fit but really worth it.

[v2rocket_aka944]

Keep the cat, but go for an aftermarket generic replacement rather than the stock one. You will like the sound it makes. There is not really anything to be gained by not running a cat on an NA.

[Makis]

Replace my CAT on my S2 10 years ago with a second hand stock mid section from a non CAT car and am quite happy with this. Piece of mind you know that there is nothing to fail as far as performance goes, i.e. one less item to fail. However, saying that CAT are made quite solid and never had one fail on me on other cars that I have driven since. Sound wise the stock mid section sound the same as the CAT. I also changed the rear stock with an after market stainless muffler and that one is still intact after 10 years. Soundwise again not much different then stock. I did managed to gut the things out of my CAT and run it on my car for a while but did not like the sound. However, this had more to do with my engine having problems (2 valve spring broken, end eventually had a burned out valve to add to the damage). So It should sound better know (as I still have it) but can't be asked to try it out as I am happy with my current setup.

[John_AZ]

Originally Posted by v2rocket_aka944

Keep the cat, but go for an aftermarket generic replacement rather than the stock one. You will like the sound it makes.

There is not really anything to be gained by not running a cat on an NA.

Keep the cat--it is needed for the exhaust system to perform correctly with adequate Exhaust velocity!!! Referring to v2rocket's post #11
http://forums.pelicanparts.com/6288552-post11.html

Previous discussion.

http://forums.pelicanparts.com/porsche-924-944-968-technical-forum/631710-catalytic-converter.html

John

[Gawernator]

On the topic of OEM cat ($$$$ for a replacement) and aftermarket catalytic converters, how often do our cats go bad? My 83' had the original going strong, and I welded my 86's original back on in July and it passed smog pretty handily. The employee at the smog station was surprised and told me they generally start going south after about 8 years. Yet this one was 26. Is that true?

[guru944]

The stock cat is heavy, old and very restrictive to flow.and when they go bad they smell like rotten eggs. That's the sulfur smell.
Recommend a cat upgrade to a stainless steel 200cell/inch High performance type cat. That's what is used on most higher end upgraded exhaust systems. Emission legal and promises more torque and less back pressure.
Total removal may sound cool but your low rpm torque is poor. and we 4cylinder guy's need as much torque as we can get..... Later.

[djnolan]

What about the exhaust manifold? I replaced the original cracked steel header with a cast iron manifold from an early car. I am worried more about head temperature than horsepower. Would the exhaust manifold have anything to do with it running hot in the summer?

PS. this is a 85.5 N/A

[djnolan]

here is some good info:

http://forums.pelicanparts.com/porsche-924-944-968-technical-forum/268798-more-na-exhaust-manifolds.html?highlight=exhaust+header+temperatur e

[skyhawk5421]

I've got a gutted cat and a turbo catback on my 84. It's insanely quiet given the fact that the whole system is straight-through. I didn't think much about any kind of exhaust science, I just wanted something better flowing for gas milage