Has anyone removed one ('87 300D)?

On the 603 build, I'm looking at the exhaust. It has a very clean & clear Catalyst (the one in the exhaust, not the trap-ox, it was changed).

My dilemma is whether to install it on the car. Seems a clear one wouldn't impede exhaust flow on a fairly stock engine to reduce power, and I'd really like the keep the exhaust as clean as possible.

So, has anyone removed one so that you have before & after comparitive performance knowledge?

Also, I have to believe it acts as something of a resonator or muffler, did it make any difference in sound / resonance? I don't want a 944 drone to the car, like it quiet.

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Gone to the dark side

- Jeff

It's out. $30 and straight pipe did the job at muffler shop.
Hardly any change in sound, just a *little* in the low end, and mostly off-idle. Once you get on it a bit (maybe 1000+ RPM) the difference in sound is negligible. Now, I forget what it used to sound like and what it sounds like now is very OK. I don't like loud either. I like quiet. No highway drone or anything to worry about.

For the record, my ox is out, and replacement was done before I got the car. And the rest of the exhaust is stock. I do think I've got a crack developing in the flex joint at the downpipe, it's getting a bit louder there - after I had a mechanic do driveshaft work who dropped the rear of the exhaust a bit, while leaving it attached at the front. I hear this sound more from the floorboard area of passenger side. Again, tolerable but louder than I like. Next time I drop exhaust that joint is going to be replaced.

I also did other mods all at the same time, so I can't positively attribute some % gain due to minus cat alone. It was kinda icing on the cake. The cake included a bunch of things that are also easy to do. I took out the air metering box and put a piece of 3" straight pipe in its place, unrestricted intake. Don't even think of wasting your time changing out the stock airfilter setup, it's better than most aftermarket for airflow. I also shimmed ALDA, and advanced IP timing (by ear). I also adjusted the bowden cable on tranny. Oh ya, shimmed shut the EGR too.

Stock fuel side. Except I upped the injector PSI, to maybe 10% over stock upper limit. And put Monarks in - good return on investment there. I had a dribbler and a couple poor patterns - they're all fine now! Took care of rough and smokey start.

All these together put a huge smile on my face. My "old man" car could now chirp the tires on dry pavement. And my 0-60 times went from "lah dee dah" to "that's better!"

Lately, I spliced a manual boost controller into the turbo wastegate line and dialed it in to about 12psi. On the high side of stock. That made little detectable difference, but I see my boost coming on with a steeper ramp so it's full boost sooner, if the fuel can somehow catch up to it sooner. But for the $20 or whatever... maybe added an ounce or two of foot-pound to the torque curve.

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Cheers!
Scott McPhee

1987 300D