alex,
thanks for checking on the rattle. from what I know it only happens on the gts model. maybe the pipe diameter is slightly different? the stock 2ndary cat pipes are 6 cm across.

so here's my attempt at some vid/sound. vehicle is warmed up so no rattle. pulling away from the corner in second gear, not in sport mode, PSM off.
this is with fabspeed cat bypass and fabspeed cayenne muffler

http://www.youtube.com/watch?v=bHVvselwhSY

http://www.youtube.com/watch?v=KLkwafTgusU

 

ive got the rattle as well on cold startup...6 speed mt

 

Sounds great wow

 

Does that sound is with the factory muffler and Fabspeed cat delete only?

 

z145433,

Thanks for your videos.....Your setup sounds great! Nice and throaty without the rasp of the stock mufflers.

Is the sound much louder when you're in Sport Mode?

 

Yes, they can, and I would suggest they do. IMO, For one thing, the flexible connectors to the headers are very expensive to replace if they wear prematurely. I personally am not comfortable with leaving that length of pipe unsupported.

And when I had a shop fabricate a hanger for my 06 V6, the rattle diminished by at least 60%.

 

Alex,

How can you possibly say that you've NEVER hear about a rattling problem with your secondary cat bypass pipes? People have been complaining about it for at least 4 years, and on multiple forums.

 

I just had the fabspeed bypass pipes put on my 2005 CTT. I have no rattling whatsoever. Also the sound is very deep and throaty. I have heard sound clips of norm asp cayennes and they seem to sound raspy. The CTT does not sound raspy at all. It really sounds great at all rpm's including cold idle.

 

Polar993,
there is still a raspy sound from 3800 to 4300 but I thought that existed with the stock setup. its almost like the gts has a 993 type varioram system that kicks in at 3800 rpms. that's why I thought the best way forward is having an exhaust built for the gts instead of using the cayenne s or turbo exhaust.
the sport button activates a valve in the stock muffler that opens an extra passage increasing sound. the fabspeed muffler doesn't have a valve so the sound moves straight through. I just zip tied the vacuum tube to the underside so its out of the way.
so now the sport button only affects the suspension, transmission and engine management, no real change in sound except for the shift points being different.

as for the rattle, when I first installed the bypass pipes I thought for sure I'd done something wrong. every time I had it started cold I would crawl under and hold the pipes trying to figure out where the noise came from.
the pipes don't actually vibrate enough to make the noise. it seems to me that the rattle sound is an echo of sorts from the muffler, almost like feedback from a microphone as the engine settles itself after a cold start.

 

There is NO DOUBT about rattling issues with this product.

Caveat emptor - I'm having a "debate" with Alex right now about damage to the flex pipe connected to my passenger side cat.

 

Anybody know if these motors have an airpump to help out with emissions upon start up? I know on my 996TT there is a nice "rattle" on cold start due to the airpump opening up. After the motor / pipes are warmed up it goes away. Just throwing it out there as an idea but I have no idea if this is / could be the culprit.

I have a set of bypass pipes in the mail for my CTTS and am anxious to see how it sounds!