Just curious! Wonder if it would cut the noise down somewhat or would it be like a straight pipe.

why??? I guess it would depend on the convert. Usually they sound like a car that needs a muffler.

I would be very careful about using one on a non-controlled car. They are designed to 'burn' exhaust gasses thru catalytic action. Yopu don't want to just throw one on behind something with a lopy cam for instance. They are also not the best flowing unit, and there are plenty of mufflers that flow better and are designed to quiet the sound.

The SRT 4 only had the turbo, a cat and a resonator for sound, no muffler.

The kids at school w 318 dakotas take their mufflers off and just run the cats. Sounds good. kinda like a turbo muffler.

only reason why i'd run one is to have a 'test pipe' for emissions.

Other than that, most of our cars run way too fat to run a cat, it'll make that thing g-l-o-w

Scrap the converter and buy a Cherry Bomb and some Beer

Thanks, I was hoping someone had tried it. I have a case where I only have space for a muffler or converter but not both and I have to pass emissions. So..... Having a stock 318 that's running pretty lean to start with. I don't think the cat will be burning too hot. I might just try it!!

since you have limited space
it may not be possible
but a catalytic converter
can certainly be used like a 'resonator'
and will kill off noise in a
certain rpm range
depending on the inches of length
from engine exhaust port to where the
catalytic converter greatly expands inside

there is also a noise effect
that depends on the distance
from catalytic converter outlet
to exhaust tip
... here it is best to avoid anything between 55 and 75 inches if you don't want
'highway cruise drone'

I ran my '96 ram with the cat only, then split to dual 2.25" straight pipe out the back. it wasn't too obnoxiously loud. those cats are kinda restrictive though. a higher flow cat would've probably been too loud.

I have a 2002 non-Mopar truck with a V8 and just run cats. It sounds pretty good and is surprisingly quiet at idle. My exhaust is cut off at the rear of the extended cab. Everything about the engine and exhaust is stock other than it being cut.

For those who were around in the '70s, about 1978 or so Mecham Pontiac in Phoenix (IIRC) built something called the "Macho TA". They ditched the muffler and let the cat do all the sound dampening. I didn't like the sound but the cat did reduce sound somewhat. Of course in the late '70s the GM cats were the pellet type, now with the monolith type it would probably sound different as well.
R.

Some of the 80s FWD cars had a cat and a resonator only. Right now our 84 Ramcharger has a cat only. The 318 sounds pretty good. I will probably run a similar system on the 360 in my 79 Power Wagon, but with larger pipes.

My 81 Charger 2.2 had a converter and a resonator, factory.

My 74 slant "FartDart" is running a straight pipe out to the bumper. It sounds neat, except for that damned cracked manifold

This hasn't been asked yet, but whats it going on? This may help determine the sound you may expect. Also, the bigger (as in length) the cat, the quieter it will be.

I had an 82' D150 w/a warmed up 360 that I put dual's on. I ran a cat on each side without mufflers (I had to run cats to pass emissions). It was a bit loud but not too much. I thought it sounded pretty good.

Unless you have a closed loop system or an air pump I think you will just melt the cat.

I would think that pumping air into a Cat would make it run hotter(more oxygen) not cooler? A properly jetted carb shouldn't cause a problem should it??

A proper working cat needs the exhaust mixture to cycle from lean to rich, back and forth. Rich enough to get a little fuel in there, then lean enough to get a little oxygen in to burn it off.

On a late model car this can happen several times a second

the NOx section of
a '3 Way Catalytic Converter'
does indeed need the rich/lean alteration
but old fashioned 2 way catalytic converters do not need to do this to reduce CO and HC pollution

A hollow cat sounds good and not restrictive and with a properly tuned engine you can still pass an emmisions test.