sanchez

Has anyone "gutted" their catalytic convertor? (removed it, knock out internals, reinstall it) Do "pre-mufflers" or "test pipes" offer better flow than my less elegant alternative?

Todd
1981 911SC

Matt Chamblin

I have on my SC. It works better than the Bursch test pipe I had on for 10 minutes. Plus it still passes the visual and tail-pipe emission test.

It won't increase HP to where your neck is snapping back into the seat. BUt it does increase the noise level some.

Dennis Diem

I had an 82 SC, when the cat went bad I had the mechanic punch it out. Car still passed smog with about 50% margin, the only down side was the added noise.

Good Luck

Wil R. Ferch

Hi:
General consensus from those who *know*, like B. anderson, indicate test pipes don't really do much...Porsceh Euro pre-muffler shold be good for 4-6 hp.

---Wil Ferch

sanchez

Wil,
I'm probably beating the proverbial dead horse with this topic, but I'm the kind of person who collects all the info I can on a subject before making a decision. I appreciate your reply. From what I've read, the pre-muffler seems to have a more efficient "scavenging" effect than the test pipe or "gutted cat". Can anybody confirm this for me? I want to keep my stock heat exchangers, so I'm looking for the best solution on a single in/single out exhaust.

Todd
1981 911SC

Ed Hughes

I just put a Fabspeed Euro pre-muffler on, and feel more pull at 3K RPM, and maybe a little quicker wind up to redline. Also, a definite deeper tone to the exhaust. A bargain for less than $250, and it is a beautiful piece of metal.

Ed Hughes

I just put a Fabspeed Euro pre-muffler on, and feel more pull at 3K RPM, and maybe a little quicker wind up to redline. Also, a definite deeper tone to the exhaust. A bargain for less than $250, and it is a beautiful piece of metal.

mschafer71

I gutted my cat in my 88 3.2 and saw the oil temps stay at or below the first white line above the lower white bar on the oil temp guage. Prior to gutting, it was between the two white lines so it definetly runs cooler and seems to have better throttle response. The noise level increase is not that noticeable, still have on my stock muffler. I have a by-pass pipe and new O2 sensor I am putting on soon, and will report back with any pros or cons. Good luck with the exhaust nuts and bolts. I had to drill thru my nuts to get them off, but they should be replaced anyway. If you take off the rear valence it is a much easier job. If you take off the muffler you can drill out the ceramic core with a (very long 16") one and one-half inch bit(put ten or so holes in the core) and pull out the core pieces and the steel mesh(PITA)that surrounds the ceramic core. You will have to be patient in breaking up the core and pulling it out the rear. Make sure you start up the car to blow out the dust and crap before you reconnect to the muffler. Plus you get to heard a unmufflered 3.2 roar! Just don't do it at a unreasonable hour of the day! Mark Do it!

Wil Ferch

Sanchez:
I too have hung on every word that can be substantiated by those "in the know". I have records of B. anderson statements that a test pipe does next to nothing, and a proper Euro pre-muffler adds 4-6 hp. Can't speak to the Fabspeed device, but if it's built and shaped like a Porsche pre-muffler, it should work as well.
Personal data point...added a Euro pre-muffler and removed cat on my 85..a *definite* improvement especially in mid range rpm.
---Wil Ferch

Wil Ferch

Sanchez:
I too have hung on every word that can be substantiated by those "in the know". I have records of B. anderson statements that a test pipe does next to nothing, and a proper Euro pre-muffler adds 4-6 hp. Can't speak to the Fabspeed device, but if it's built and shaped like a Porsche pre-muffler, it should work as well.
Personal data point...added a Euro pre-muffler and removed cat on my 85..a *definite* improvement especially in mid range rpm.
---Wil Ferch