TT Surgeon

Joe is a good guy, he invited me to bring my car to his shop in order to test fit some C4S bypass pipes, he gave me a set for my trouble!
Now, I have GHL's on my car and was expecting him to tell me what POS they were and sell me his, but nooooo...he actually had good things to say about GHL, refreshing for that industry.

Jeff Curtis

Did you still retain the bypass pipes along with the GHL mufflers?

Must sound GREAT, either way.

TT Surgeon

I have the GHL's on the car, I will use thge bypass pipes for track days.(loud)

Jeff Curtis

So, you're saying that with the GHL mufflers and bypasses installed at the same time it's pretty loud?

I would imagine that with Fabspeed's headers, bypass pipes and the sport mufflers...it might get a little noisey then.

Are the bypass pipes that easy to take on and off for the track? ...about how long do you figure to change them out? Do you notice a performance difference with the bypass pipes?

I apologize for asking so many questions, I've driven a 996 with bypass pipes et al, kinda loud I guess, but the acceleration felt nice and strong...at the track...wondering how well a 997 will run with them?

TT Gasman

The bypass pipes replace the mufflers, so it's one or the other, and about one hour of your time.
I recently bought a set of Fabspeed mufflers, I couldn't be more pleased, excellent quality and sound. Highly recommended.

TT Surgeon

Exactly as Doug said, they replace the mufflers all together. There is a such thing as a catalytic coverter bypass tha keeps the muffler and bypasses the cats. Perhaps that's what you're refering to?

Jeff Curtis

Actually, that is what I was thinking, a catalytic bypass...I should know though, a local shop just received two bypass sets from Fabspeed for their GAC 996 racecars and I recall they are just straight pipes that bypass the cats AND the mufflers.

I'm certain that VB997 is only interested in cat bypasses and not the whole deal - my GOD, I've heard the straight thru bypasses and they are LOUD!

Thanks for clarifying DJ and C4S.

Gary R.

What good would the CAT bypass pipes do I wonder? Is it just a sound issue or do the CATs rob a substantial amount of power? I know the Fabspeeds (according to them anyway) are 28lbs lighter than the stock exhaust, which is fairly substantial. I just listened/watched their video showing the muffler bypass pipes (55lb savings) and they didn't seem excessively loud to me. They make the statement that its legal (and meets emissions also) which means the CATs are not necessasary (their claim, not mine). Not quite sure how that can be true, but assume they have tested a straight-piped 997S and can back it up.

I will say the look of craftsmanship and quality is fantastic on these pipes...

Jeff Curtis

Gary, the general consensus is that one would gain HP by removing catalytic converters from almost any vehicle, especially a performance vehicle...although a virtual debate teams exists that would argue that point to claim NO gains, or minimal gains...some claim a LOSS in power.

Either way, removing the cats from a 997 would certainlyl guarantee a GAIN in sound level!

While I'm not positive that removing the converters from a 997 will result in a power gain...I'd be willing to bet that it would.

On my 1991 911 C2 (964 Series) I use a "European Pre-muffler" (Fabspeed product) in place of the cat, it is not your usual straight-thru bypass, but a resonator of sort. My system seems to sound different when compared to another 964 that has a straight-thru cat bypass and retains the same muffler as I do, a factory Primary muffler. Keep in mind I'm talking about my 1991 911 and NOT a 997.

I would say I gained some top-end power and was able to retain MUCH of my low-end torque with this setup, of course the car is "tweaked" a bit as well.

Gary R.

Thanks Jeff.. if you get a chance check out the video on Fabspeed.com of straight pipes on a 997S. Really doesn't seem loud enough.. for only having headers and straight pipes that is. Seems like a really nice setup (for me anyway) would be the headers, CAT bypass pipes, and Maxflo mufflers.

Here is a quick link to the straight pipe video--
http://www.fabspeed.com/997%20Muffler%20Bypass.wmv

VB997

Gary, in this video Fabspeed was showing the Muffler bypass pipes. The car still had the factory cats in and that's why they made the statement that "it complies with emissions"...They removed the mufflers and installed a section of stainless pipe straight to the cat pipes. The other approach is to leave the mufflers on and bypass the cats with a section of stainless pipes...This should be used as more of a racing application on the 997.

I have the Fabspeed headers and mufflers on now and want a little more volume however the muffler by pass pipes are way too loud and the cat bypass pipes are still being researched for street applications.

The setup you described is exactly what I’m trying to achieve but the problem is the OBD2 issue. This is not an issue when used on a race car however it might bother you if your check engine light comes on and doesn’t blow out on your brand new car. Fabspeed is saying that for now the cat bypass pipes are best if used for track applications on the 997 or if you understand and are ok with the fact that you might set off your check engine light.

There is another alternative I’m looking into if all else fails on the bypass pipes but it’s expensive…

I’ve been exchanging e-mails with RUF, Techart and Gemballa in Germany on their sport catalytic bypass pipes, which are less restrictive catalytic converters that will not set off the check engine light, comply with emissions and turn up the volume a few notches. This would be my last choice as these are very expensive solutions and I would much rather keep my system all Fabspeed.

Gary R.

Thanks for clearing that up for me VB997 (and thanks for the PMs on the pedals). I'm in no rush at this point, I think I may add the cold air kit and the K&N filter soon but i'm going to "wait and see" what comes out for the 997 exhaust mods. I really like the design of the Fabspeed header better (only can compare pictures) than GHL's, which looks more like the stock header - but in polished 304. Bends and collector seems smoother to me.

Richard in Colorado

Looking forward to your responses!

Richard in Colorado

How much? Could you install them yourself?

BD997

lets see some pics with your Maxflow exhaust on...