Muffler bypass pipe

[Paul Shepherd]

Hi I am thinking of fitting one of these to my 3.2 carrera and wondered if anyone had done this, and if so how noisy is it because it is just a straight pipe straight off the cat converter

[christiandk]

I did the "investigating" during the week, and found out that I dont like the sound. Somehow the car does not sound like a 911 with the bypass muffler pipe - just sounds like....well a car without a muffler.

Check the videos on youtube.

[PDACPA]

I have the catbypass with a GHL. There is an increase in sound, but I like it.

[ivangene]

muffler by-pass means exit right after the cat (or cat delete pipe)

makes the 911 sound like a tractor

awesome for farming - not so awesome for street, track or inside the car

[pranderson]

I have a fabspeed set up that replaced my cat and muffler on my 91 Turbo. Its pretty loud, but I like the way it sounds especially when you have your foot in it. I think the turbo muffles the sounds a little bit, I think if it were any louder I wouldn't like it. Its already hard to have a conversation with the a passenger. but I usually drive by myself so its ok for me.
I have another Fabspeed set up on my 83 SC that replaced my cat and muffler thats much quieter than the turbo. Not sure what they called it at Fabspeed but it sounds great. They were actually pretty helpful there when I ordered my second exhaust setup I originally ordered the same thing I had on the turbo and they called me to verify that what I ordered was actually what I wanted because it was apparently going to be very loud. They said that they would hook me up with a system that performed and sounded great and they did exactly that---I'm very happy with both set ups.

[PDACPA]

I am not sure what some of you guys are referring to, but mine does not sound like a tractor and though louder than stock in the cockpit, you can still carry on a conversation and listen to the radio.

Sorry for the poor video, but I am at work alone and hard to hold the camera and give the engine some revs.

3.2 with Cat-Bypass and Dual out GHL

[ivangene]

muffler by-pass is NOT cat by-pass (or cat delete PIPE)

muffler by-pass is when you dump the exhaust right after the cat - NO MUFFLER

this IS the "muffler"

[PDACPA]

Mine looks like this under the driver side rear quarter panel:

Catbypass

And is what I thought Paul was asking about.

[ivangene]

awe - those are CAT delete or pre muffler (see even the link calls it a Catbypass) - I agree that I think that is what he is talking about, but that isnt what he said

muffler bypass is a whole nutha enchilada - LOUD

[PDACPA]

Mine has a decent roar, especially when you get on it and crank the RPM's, but it is not waking babies and breaking windows when I drive through the neighborhood.

[BHP231]

Don't run a muffler bypass pipe. It won't conform to a lot of track dB regulations and certainly won't conform to street laws.
I put on an M&K cat bypass pipe without the bolt in the O2 sensor hole and the sound is great, plenty of crackle on down shift and nice engine roar under acceleration without being obnoxious.
It's hooked up to a Dansk one in one out Muffler, stock headers.

[Paul Shepherd]

thanks for the replies guys, I was meaning the muffler bypass as in the picture whilst retaining the factory cat but by the sounds of it (no pun intended) it is going to be to loud. I just want to get a better sound without spending a fortune
Thanks for the video link to the car sounds great

[PDACPA]

@BHP231 mine has the 02 sensor hole and I installed a new one when I swapped it out. Have not had any issues with the sound and violating street rules (forget if I had it on when I tracked it at Sebring).

For a short period of time, Florida had this registration check and you drove in and they walked around the car with a mirror to look under to make sure you had the cat and they would stick a probe in the exhaust pipe and, I assume, measure smog/pollution ( not sure if the same as up North). I passed every time.

[KC Chief]

Paul, it really is personal preference and what you are used to. My other cars are muscle cars, and the muffler bypass on my car, with the stock cat, is awesome to me. You will learn to control the sound with your foot. And, it's cheap! I say try it. People keep telling me I will get tired of it, and 6 months in, I'm not. I recently bought a cat bypass, and when I install it I'm going to experiment with some car chemistry inserts.

[stephen1070]

I have the fabspeed unit shown above by PDACPA and the matched wong chip on an 89 3.2 - just what the car needed... sounds like a flat 6 without the crap required by the feds...

[BHP231]

Originally Posted by PDACPA

@BHP231 mine has the 02 sensor hole and I installed a new one when I swapped it out. Have not had any issues with the sound and violating street rules (forget if I had it on when I tracked it at Sebring).

For a short period of time, Florida had this registration check and you drove in and they walked around the car with a mirror to look under to make sure you had the cat and they would stick a probe in the exhaust pipe and, I assume, measure smog/pollution ( not sure if the same as up North). I passed every time.

Lucky for me there are no cat requirements in Australia so noise is the only thing to think about.

[Steve W]

I know a guy that's been running that setup on his 87' for the last two years off the factory cat. It's loud, but tolerable if you're used to loud track prepped type 911s. I wouldn't do it for a daily, but for an occasional fun street car/part time track car it sounds fantastic at the track like a 911 with headers passing though a straight through style muffler, not as loud as the track cars with a completely straight open unmuffled exhaust because the cat baffles the exhaust flow. On the street, it doesn't really drone in the car, it's just very aggressive and loud, probably 10-15 db over stock. For me it's tolerable, but I'm used to loud cars, but I'm guessing for 80% of the guys here, they may think otherwise. The gain is about 25 lbs off the rear end, and with a proper remap, a 7 hp gain over the stock muffler for not much $.

[Paul Shepherd]

I'm thinking that I will try it as its only $165 as I don't mind noisy cars and it is not a daily drive, just take it out for fun. I have the muffler off at the moment because I replaced the cam oil lines and the oil pressure unit and it drones a bit but hopefully this will improve once the exhaust gets out the back as the cat finishes under the car. Another bonus is the missus won't want to drive it if its loud

[mark4ton]

Here is a video i shot today of my 3.2 sitting at idle.

1987 Porsche Carrera 3.2 with Fabspeed bypass - YouTube

[PDACPA]

I went out and shot a video to give some comparison.

Here is my Fabspeed bypass with a GHL Dual out on a 1989 3.2.