Silvertarga

I am currently running a Fabspeed exhaust with dual outlets and am wondering just how much louder things will get if I install a cat bypass ...does the bypass really increase decibel level ?
What are advantages/disadvantages of cat bypass I am not worried about emissions testing as I am exempt from same

RDS928S

There is no downside except exhaust smell(unburned hydrocarbons etc)

I have the Fabspeed maxflo mufflers & no cat x-pipe. The car sounds awesome. Nice rough crackle pop idle but fairly quiet up unti 4k then the roar starts. Very nice.

Good Luck

Amroth

I have a gutted cat and when compared to a car that doesn't have it, I think it sounds deeper and beefier, but not THAT much louder. I say go for it. I just got my primary bypass and and very curious to how it will change the sound!

964russ

Iam running a cat bypass and a techart primary with standard secondary/last box.
The bypass makes a lot more noise, with cat its about 102db, without 112db (tested at oulton pk 115db?) the bypass removessum low end pull but gives sum top end.
Proven more power, dynod at 278hp, was 256hp, thats with remap and cat bypass.

Silvertarga

I am looking at the Fabspeed or the Schnell from Vertex. both about the same price, I knew I was gonna do it unless someone had a definite horror story, The Fabspeed exhaust sounds beautiful as it is...so the money I save on not upgrading the speakers can go to cat bypass ...really cant hear the stereo with roof off anyhow!

Joe@Fabspeed

Silvertarga.......that is a GREAT photo of your car in the snow. Please send some more true artwork.

Our 964 catbypass pipe is actually a EURO premuffler. Normal 964 catbypass pipes are just straight pipes and very loud. I designed a pipe that looks like a catalytic converter and inisde is a perforated resonator that gives a modicum of backpressure for maximum torque and power. The resonator/muffler also attentuates sound. If one ever had a visual inspection it looks like a polished catalytic converter with an oxygen sensor bung and everything.

I hope you had a great weekend. Need more snowbound Porsche photos!

941MXVET

I just placed an order for a Fabspeed sport cat for my 964. I haven't really seen many reviews for this product, but thought I give'r a try. I think that the reports of a gas-y smell turned me away from the complete cat bypass. I'm hopeing I see some improvement in both sound, and HP.

Silvertarga

The fabspeed exhaust system I am running sounds great and is very well made so I am leaning towards the Fabspeed by pass as well,

Exhaust system took less than a six pack and box of band aids to install ...no problems whatsoever..hopefully the cat bypass will be a breeze

Any problem with running without the heat shields that the standard cat has?

Laker

I believe some chips claim to be able to eliminate the fuel smell.
You want to keep your shields on to protect your tire

911Jetta

Some chips eliminate fuel smell? Good news, which ones? I have a 93 Wong, it's programed for a bypass, but I've been on the fence because of the smell. I need to check Wong's site again to see if it's mentioned?

Never even thought about the tire being subject to the extreme heat of a shieldless bypass, was only worried about the motor.

Silvertarga

Well that kinda puts the kibosh on the Fabspeed , it does not look like it has the brackets for heat shield , The Schnell does..

Hate to go with the Schnell as it is not US made..

plambert

RE: need for shields:
What's the surface temp of a cat vs. that of a cat bypass vs. euro pre-muffler vs. test-pipe?

Laker

I take that back... I thought I had read that as a benefit but can't find it.. apologies

stinkydog

I actually notice a richer fuel smell from my exhaust with my SW chip. Just for the first 30-90 seconds after startup (depending on ambient temperatures, etc).

boxsey911

I'd heard it was the other way round....shields needed for the cat because it runs much hotter than a bypass? There are no shields on my bypass and I haven't noticed any problems with the tyre.