daking

I have a cat bypass + primary cup bypass.
I also have a Gpipe, never fit on my car... It's a good idea put it on ?

964 race cup car have cupbypass and Gpipe bypass but have sport cat... Any "backpressure" REAL problem for me whit another bypass ???

I think it will be a bit loud..

MitchB

I assure you it will be loud.

ducnine

I have a G-pipe on my car and it is plenty loud....but in a good way

kgorman

You will likely lose power, I think Tom did a dyno a long time ago and it showed to do two of the 3 changes, but not all 3.

etom

I tried all three . . . for about 10 seconds. WAY too loud. G-pipe OR primary by-pass. One OR the other. But not both.

Jim Howley

Have a look at this if you want to know what it sounds like. I think it sounds great but I couldn't live with it on a daily basis.

http://uk.youtube.com/watch?v=iQx649QcwOg

daking

Really really really loud, probably too much..

mmmm.. Lose power.. maybe in some range of idle. But I think it'll have some improvment in other range..

Anyway I have a non standard chip and tuned motor, I think It will be necessary re-program chip to add gas in the "mixture" air/gas.

There is a thing more important... lose weight... primary, cat but specially secondary are heavy...

In addition to sound, which seems really excessive, the important thing is to know if it can cause other problems.

I think the best is to do something like this;-) https://rennlist.com/forums/964-forum/218771-cracking-the-primary-muffler-and-turning-it-into-a-beast.html but now I have not enought free time :-(

I maybe first try Gpipe...

mpeters951

I've done all bypasses; meaning I'm left with standard Cat into Dansk primary b/p, Dansk "G-pipe" and Dansk tip. Way too loud ? No bloody way ! Have I lost an ability to sneak into the garage after a late nite boozer w/ the lads ? Absolutely.

Is there a power loss ? I'd ask you folks to recall what Porsche Motorsport was running for exhaust with the advent of the 964 Super Cup cars. And what was that ? It was stock cat, and deleted primary and secondary mufflers.

Are some in this thread going to propose that Porsche Motorsport was advocating a power loss for the Cup cars ? I think not. That said, I do not yet have dyno pulls to substantiate my own spec. but at this point I'll defer to Stuttgart and continue to believe that the Super Cup exhaust config, obviously coupled with the DME mods, was done for legitimate performance reasons.

I wish that I had a sound clip to share but I can tell you that down to the last, the local Porsche zealots have repeatedly given a huge thumbs up to the sound. Admittedly I wouldn't want this is a daily driver config as I've also removed all sound insulation under carpets (now Perlon felt thoughout) and binned the (above) engine sound pad.

Driving IS an event. But that's exactly the raw experience that I'd sought.

daking

after reading your post....
yes....
I did it...
G-pipe installed !!!!!
ah ah ah ah!

(20 minutes DIY work, very simple.)

it is much noisier than what I thought, (too much, too much, too much :-D)
it's seems like two harleyD.. but non standard HD :-)

However original muffler is really heavy:-(

I tested it only 30 minutes.. without very strong acceleration.. I am afraid to loose everything or going in prison.. ahahahahah

I haven't all sound insulation too, and in the cockpit there is too much "low frequency sound" , and I must drive with windows lowered to delete this effect.

From outside, the sound is better.
I have done a small video :-)
I'll post as soon as possible so you can see what I mean.

Actually there is a power loss in hight "rpm / idle" (..for my sensation), instead in low it seems to be more powerfull, expecially after changing the gear.
- If someone wants to do this modification must change "cpu / Chip" program.
This afternoon I'll test better.

However I'll remove G-pipe in two days.

My exaust will be: cat bypass, mod. primary muffler (with a basic linear silencer) and G-pipe, a reasonable compromise between performance, noise and weight.. what do you think ?

964russ

MY car is running a straight threw pipe to the last box.
It runs fine but is very loud.

anto1150

Has anyone compared g-pipe-only against primary-only? Performance enhancement, sound and weight saving on both solutions?

Bull

My 964 Cup ran very well with no cat or any mufflers, but the ECU was significantly different from a street car.

The RSA, with headers, no cat, a B&B primary, no secondary, makes a joyful noise, but is not too loud even for my wife.

ChrisWhittle

My 964RS has cat bypass, cup primary bypass and had G pipe = 112 dB

Now has secondary exhaust in place of G pipe = 105.6 dB

With additional Will Norman tail pipe muffler = 103 dB ---- ad this takes around 5bhp out of the mid range and 1bhp out at the top of the curve.

Rolling roaded at 335 bhp and 420nm torque. Motec + 1/2 from 9M.

DLCrow

might want to check out info. from Joel Reiser on the PCA.org forum - he basically says primary or secondary, but not both. Removing secondary (g pipe) removes weight and adds torque - I did this and the sound is great and the run up the tach is great.

deep_uv

I replaced my primary with a bypass first. It made the car sound alot better, but no noticable difference in power. Then I replaced my cat with a cat bypass. Sounds even better and resulted in a noticable difference in power, really woke the car up. 243 at the wheels.