all623

I plan to use original headers and maybe use a catbypass later. I had narrowed choices between the two below but now not sure-

-B&B primary muffler that bypasses secondary (only option I believe if you use original headers they ahve)

-GHL secondary muffler which bypasses primary.

GHL told me they recommend their primary muffler setup as the above B&B. They said it was the better option but didn't explain why, just commented they are not trying to "sell me" on anything. It was the owner I was speaking to.

The reason I was considering GHL in the first place is the pitch seems higher and tuned using a secondary muffler with primary bypass- reminds me of a 2.7 sound.

If I go with GHL's primary, as they recommended, will it not sound similar to the B&B and so what's the difference? Anyone heard the GHL primary (C24CSRS3) and do you have any advice or recommendations, any sound clips. All I believe I have heard out there are of the GHL secondary.

Not so much worried about HP, just don't want to lose any.

LouZ

I'm running with the Fabspeed dual outlet exhaust bolted directly to the stock headers.

DEEP THROATY sound! There are soundclips on their website.

RonCT

Neither... Leave the primary, remove the secondary (connect with a G pipe). Extremely inexpensive and sounds fantastic - very Porsche OEM / Cup. Want more, change the cat with a bypass...

Added: The G-pipe is $153 w/ PCA discount at Automotion - very reasonable exhaust mod. My C2 has this and the cat bypass and it sounds unbelievable.

DLCrow

agree with ronct - leave primary - remove secondary - insert G pipe. sounds wonderful - even improved the rpm sweet spot.

CarreraCup03

Use a primary muffer bypass ... leave the secondary muffler in there. Replace the cat with either a race cat or euro premuffler (cat bypass). Primary muffler is heavier and directly in the back of the car .. so you are removing weight from the best possible spot. That is how my 964 usa cup was set up .. and sounded great and was very fast.

deep_uv

+1 This is the way to go.

james944

I don't know if this will help since it doesn't compare the specific options your considering, but post #2 in this thread has a link to clips of various bypass combinations:

https://rennlist.com/forums/964-forum/229566-muffler-bypasses.html

Not to hijack the thread, but I'm interested in bypassing one of my mufflers too, I just can't figure out which one. I'm not going for a specific sound (although louder will be nicer), mainly the weight savings. Removing the primary seem like the best choice, because it is exactly in the rear, but it's bypass would have to be heavier (it's longer than a g-pipe), and some people say the secondary muffler weighs as much, if not a little more than the primary:

https://rennlist.com/forums/showthre...20muffler+22.8

If the cup cars were set up with a primary bypass and a secondary muffler that's appealing, but if the other is significantly lighter...

thoughts?

CarreraCup03

The primary muffler is heavier than the secondary ... and a "cup bypass pipe" is the pipe that bypasses the primary muffler.

ltc

^ + 2

Meares

i've got the stock cat, fabspeed primary bypass and have removed the secondary muff and the tip. it is loud! but DAMN does it sound good!! especially at WOT....i probably shouldn't drive it on the road, but i'm getting used to it

all623

It does make sense losing the weight under the rear bumper by replacing the primary with a pipe. I guess the secondary would help balance the weight of the catalytic converter and driver on the other side of the car.

Has anyone heard both setups, primary vs. secondary byapss and can they comment on how they sound and which is louder. I am thinking of doing a catbypass later so I'm sure that adds even more noise.

Appreciate all the tips...

DLCrow

Following is a post from Joel Reiser on this issue - for what its worth---



I don't like to bypass both mufflers on the 964 with stock heat exchangers, especially for a street driven car. The saying goes that replacing the primary muffler is good for 10hp and 10dB (decibels of sound), replacing the second muffler is good for 10 foot pounds of torque (better acceleration) and 10dB, but replacing both makes 20dB, and no power at all. Truth is, it's all guesswork unless someone has dyno'd your motor with the changes, or if yours is truly an exact copy. But for a street driven car, I prefer to just bypass the second muffler, only. You get a deeper richer sound, and better acceleration. The car "pulls" better. Whereas bypassing the first muffler (the center muffler), seems to be the ticket for a track car if all you need is more top speed. That would be in the ballpark of 170 mph.

Joel Reiser - PCA WebSite - 11/19/2005

deep_uv

The primary muffler is also more restrictive than the secondary. The cat is most restrictive of all 3.

altarchsa

A recent post had links to .wav sound tracks for all the combinations of removal / replacement, including one from stock. If you can't find it, PM me and I'll post them. I copied them onto my hard drive since I am considering the options. The primary bypass with cat bypass later makes most sense and sounds best to me.

Meares

92 C2 Cab #1 stock cat, stock prim. muff, 2nd muff bypass, RET tip...VERY nice sound...not too loud but people look around...deep and rich

92 C2 Cab #2a stock cat, prim. muff bypass (fabspeed,) stock 2nd muff. and tip. just a little bump in exhaust note...just not enough.....feels like it "freed" up the engine a little

92 C2 Cab #2b stock cat, prim. muff bypass (fabspeed,) no 2nd muff. or tip...i just turned the pipe down....it's loud! sounds great! people REALLY look around....i sometimes feel like a jerk because it's so loud...the idle is great...WOT is great...probably more suitable for a track. HARD to drive with a hangover! car feels faster...probably just me though...

i'd REALLY like to know how a g-pipe and stock or aftermarket tip would change the sound!