fogcity123

Just searched the info on this option and would like to do one or the other, mostly for a sweeter sound. Can someone tell me:
1) Any negative affects? (Such as later having to smog the car here in Ca?)
2) For a daily driver, non auto x er, which one makes more sense to do?
3) Anyone know where / who can do this for me in Northern Ca SF Bay area?
Thanks.

fogcity123

One more question:
It's mentioned there are "kits" for doing this. Where are they sold and does that allow me to remove and then later (if need be) I can re-instal the removed muffler, without the need for cutting / welding? In other words I can do this myself? (okay maybe that was 3 more questions)
Thanks

Jim Howley

At the moment I have a primary bypass on the car which sounds great but I did prefer the sound of the secondary bypass that I had on my last 964, it seemed to be a little louder and a little deeper sound.

As for fitting either can be done by yourself if you wish, it is only a case of undoing a few bolts to replace either of the boxes and can be put back to stock without any problems whatsoever. There is a DIY thread on fitting a secondary bypass (G-Pipe) here.

For replacing the primary silencer you need to remove the 2 straps that hold the box to the back of the car and simply manouver it out from behind the bumper. Any primary bypass pipe should come with new straps which wrap around the same mounting points as the factory silencer. The picture below shows a car fitted with a G-Pipe and you can see one of the straps that wraps around the primary silencer.

ACSGP

I'm going with the primary by-pass shortly (cars here pre-92 didn't have cats) simply because the workshop has a new RS replica by-pass pipe.

But I'm concerned about the possibility of the drone in the cabin. Any thoughts?

springer3

No drone in the cabin of my 92 with primary by-pass, and stock everything else. By driving slowly, you can be polite in areas where the noise would offend. I do no notice the louder sound until I raise RPM and power settings.

rdean

See my post from 04.04, "RSA Garage pics". I have just completed...
Cat by-pass install
Cup pipe install

Factory Secondary muffaler remains
Open air box with K&N

The sound is great! Not too loud, it's just right
The throttle response appears to have significantly improved
Fabspeed indicates +16 hp,... TBD
No smog test in NYS

Very satisfied.

rod911964

911Jetta

Video above: the sound of the primary bypass through the gears.

Both are easy installs and will not drone.
Primary bypass is what the Cup cars ran and has a nice sound (it not over powering, so you still hear the various notes of the engine as it runs through it's rev. band). The secondary bypass also sounds nice, but with a much lower, woof-woof sound. Again it's a nice sound, but of a different nature.

People love either so you really can't go wrong.

raspberryroadster

very pleased with primary delete (aka cup pipe)....as long as cat is maintained should be no issues with passing air care.

fogcity123

Great! Thanks for the advice. I'll go with the G-pipe option (still confused if that means primary or secondary - assuming the muffler closet to the tailpipe would be dubbed the secondary?) So where's the best place to purchase this little kit? Also, reach in an old post that after this is done I should drill holes in the airbox and remove replace the neg battery terminal to "re-set" the computer? Agreed? And, what's the trick for drilling holes in that airbox?

Jim Howley

Check out the guide here.

fogcity123

Okay. G-pipe on Pelican for around 2 bills. I think I'll go for that route.

Marc Shaw

I had a G-pipe (secondary bypass to replace the suitcase muffler just before the exhaust outlet) but removed it as it droned a bit. I switched to primary bypass (cup pipe) and loved it but removed it to install a full Fabspeed exhaust.

Marc

wolv

The G-pipe on Pelican is pretty cheap. Anyone know if they have or used to sell the primary bypass? They don't seem to have that listed.

Paulie964

look around for some used pipes ... I found my G pipe for 50 bucks on ebay ...

C2 Madman

I just had the Fabspeed headers/muffler/tip installed on my '91 C2 and it has noticeably more torque, revs quicker and sounds great. It is loud in the cabin from 2000 - 2500 RPM's, but it's more of a roar than a drone; true sports car sound.