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There is simply is no BEST Exhaust for a GT3 or for any car for that matter. The question is invalid and therefore the answers are very subjective.
The same subjective question could be "Who is the world’s most beautiful woman? What vineyard produces the world’s best Cabernet? What company manufacturers the best sports car?”
These questions cannot be answered quantitatively and or qualitatively.
Here is the empirical study and results for Porsche GT3 and other cars. I have been a Porsche Club member for over 30 years.
Picture above is from over ten years ago when Fabspeed finished development on the 997 GT3 exhaust Suite
Getting more power and quality sports car sound from OEM GT3s is a matter of design, engineering, incremental dyno development, feedback from customers and setting criteria and goals.
I set the goals and objectives at Fabspeed Motorsport USA with our design and engineering department. I raced PCA and did DE for 20+ years. At Fabspeed, we are immersed in designing and engineering exhaust systems for Exotic cars and making statistically significant no BS gains from the latest Lamborghini Performante to Acura NSX TT to multiple McLaren 720S beasts.
All 997 GT3 to 991.2 GT3 cars come with 6 components that make up the OEM exhaust (8 for the 996 GT3 cars). A set of headers with ceramic catalytic converters, a pair of heavy bulky valved GT3 side mufflers, a GT3 center muffler and a set of bolt-on dual center muffler exhaust tips.
The OEM Porsche AG had to meet specific emissions laws and Swiss noise regulations, so “they” overcompensated and most likely erred with conservative sound with valves and released the car we all cherish.
Picture of Fabspeed’s Porsche 997 GT3 / GT3 RS Center Muffler Bypass Pipe vs. OEM
In December 2006, I designed the Worlds very first GT3 center muffler bypass pipe. It added +5HP over the factory GT3 center muffler. A GT3 center muffler bypass system is the simplest system for these cars. It’s simple to install and now everyone makes these parts in different flavors. Some systems that are out there lose up to -7HP from stock so don’t assume everything is the same. Typically, you break even on power. Fabspeed mini maxflo mufflers added +7hp as well.
Picture of Fabspeed’s Porsche 997 GT3 / GT3 RS Sport Headers
Then, I designed and dyno developed GT3 headers with and without catalytic converters that hooked up to the stock GT3 side mufflers. The HJS German imported 200 cell catalytic converters FLOW 93% of a straight pipe, add power, gutsy sound and do not trigger a CEL. Picture of Fabspeed’s Porsche 997 GT3 / GT3 RS Race Headers
For race competition, Fabspeed deletes the cats to save even more weight and add some power. Fabspeed Motorsport makes GT3 headers with and without catalytic converters for all models from the 997 GT3 to the very latest 991.2 GT3.
Picture of Fabspeed’s Porsche 991 GT3 / GT3 RS Side Muffler Bypass Pipes w/ Valves
Third, I designed side muffler bypass pipes with and without vacuum valves to save 40 pounds from the GT3 rear engine bay. These work great, an understatement, and save a ton of weight off the rear end of all GT3s. Fabspeed uses the exact OEM GT3 silicon carbide GT3 factory valves versus valves cheaply made overseas or valves that bust after a few heat cycles. Beware, there are very poor-quality products out there. Fabspeed USA is the sole North American importer for Helical UK valves and HJS German sports racing catalytic converters. Beware of counterfeit HJS cats and Chinese exhaust valves.
Next, I designed a rear super lightweight catback race exhaust for the GT3 cars. This system eliminates the side mufflers and rear center muffler and has an integral X-pipe to balance both side of the flat six.
All exhaust products mentioned above add significant proven power and are modular to replace individual components on all GT3 cars. Picture of Fabspeed’s GT3 OEM Center Muffler Reinforcement/ Schalldämpfer Verstärkung
Lastly, I designed a simple GT3 center muffler stiffening and strengthening brace to save GT3 center mufflers. I have been watching GT3 mufflers break apart and blow holes in the center for over 10+ years. This Fabspeed Motorsport USA muffler reinforcement / stiffening brace should be mandatory for all GT3 cars due to their high failure rates. It’s only $295 and you slip it behind the GT3 center muffler and tighten the two straps and you’re finished. You can have peace of mind knowing that for a small investment you have done some vital preventative maintenance—reinforcing and strengthening the Achilles heel of the GT3s. GT3 center mufflers are the weakest part of the exhaust system. I made a Video explaining this on Fabspeed’s website
My advice to any GT3 or car enthusiast looking for sports car sound and power - look for parts that replace individual parts or components. There is no need for a Bespoke system. That way, one can get GT3 headers with HJS German high-flow catalytic converters if they want more power and sports car sound and or if their cars GT3 headers ever fail and the owner gets a p420/p430 code. Fabspeed USA has a gentleman with a 2001 GT3RS that has over 100,000 miles on it and continues to drive it every day. He was on his 2nd set of GT3 factory headers and center mufflers before he came to us. All parts and tracked GT3 parts, and any cars for that matter, TIME out after a while.
Track prepped 996 GT3 using ALL Fabspeed products
For a Street car that is emissions legal and the driver wants maximum power and quality sports car sound that is gutsy and dramatic—the following would be my personal recommendation after being immersed with GT3s for over 15 years starting with the 2004 996 GT3.
Equal length GT3 Headers with the largest HJS German catalytic converters that will fit in the chassis. Fabspeed uses the very largest HJS Cats that will support over 1000 HP. Caveat emptor- I have seen German tuners and others use small 4" round mini HJS cats on 2016 GT3RS cars. Some USA muscle car companies use 4” bullet cats on Hellcats and Vettes making over 600+HP. Bullet cats are puny and will handle only 300-400HP. Despite cost, Fabspeed Motorsport utilizes the largest HJS catalytic converters possible which are 5.35" monster 200 CPSI catalytic converters. Maximum surface area = maximum scrubbing= maximum possible percentage of flow versus a straight pipe. FLOW increases are directly proportional to added sports car sound, more power and long-term emissions compliance.
Next I would get a set of valved GT3 side muffler bypass pipes. These immediately save over 40 lbs. (19 kg) from the rear-end of these cars. I would then reuse my OEM GT3 center muffler and add a GT3 muffler reinforcement and a set of 4" 102mm rear tips to finish off and fill in the center outlet. That’s it, it’s all done, and nothing more can be gained. All while still emissions legal no CEL light - guaranteed!
If I was in California or Miami and wanted to make power, GT3RSR sports car sound, remove over 55 lbs. (27kg) from the rear of my GT3 and have girls/guys hear me coming for blocks and blocks..............a Fabspeed GT3 rear catback race exhaust X pipe with carbon tips is affordable, easy to install and catback emissions legal. It’s simple and works.
When my 991.2 GT3 comes in, I most likely may do a few DEs again and a set of our Burns stainless GT3 321SS long tube headers with merge collectors and Fabspeed side muffler bypass pipes with factory GT3 vacuum valves will be my choice for immediately adding +30HP and saving 40lbs and adding virtual factory RSR dynamic rippin' sports car sound. Check out the complete system below! Picture of Fabspeed’s Porsche 991.2 GT3 / GT3 RS Long Tube Competition Race Header System
One good thing about all Porsche GT3s are they are so easy to work on compared to cars like McLaren, Ferrari and Lamborghini as the entire rear bumper covers as well as many components must be removed in order to change and or swap out exhaust components. On the Porsche GT3, you simply can swap out GT3 headers without catalytic converters to catted headers in no time.
Fabspeed equipped 991.1 GT3 at our state-of-the-art bustling 26,000 sq-ft facility in Fort Washington, PA
If I was back at the Glen trying to catch my buddies that all club raced and now all own shops like Spencer, Rick, Chris, Mike, Keith.............I would likely go completely lightweight exhaust, fully uncorked, and run Fabspeed GT3 long tube race headers and our rear 3" 76mm X-pipe super lightweight race exhaust and buy a couple set of slicks to hunt those boys down! Some of the videos from Asian manufactures that you may have seen lately simply straight pipe the GT3. The videos sound and look good, but make sure you can live and tolerate full blown wide-open race sound day in and day out.Head to the Fabspeed Website and
for detailed explanation videos on different options along with sound and power levels.
Do you all have LT Sport Headers w/cats for the .2 GT3?
And if so, what type of numbers do you have for it compared to stock headers.
We do not do the long tube race headers with cats. We have found no reason to do the long tube headers then put cats in them all the gains that you pick up from doing the long tube you lose once the exhaust reaches the cats. The reason that the LT are so fantastic is the merge collector to a straight pipe. If you put a cat in the LT it is like having a 13 line highway into a toll road with no easy pass lanes.
There are some companies that have decided to do the long tube with the sportcats in them. We have found that if you are going to keep cat's you will have the same benefits with our sport headers and side muffler bypasses.
What causes a potential power loss on some center section bypasses? How the two sides merge, if at all? That's really the only difference with a lot of 'em. Some merge in an X, some don't. Some merge with a center pipe connecting the two sides, some don't merge at all. What's the logic behind the different methods?
What causes a potential power loss on some center section bypasses? How the two sides merge, if at all? That's really the only difference with a lot of 'em. Some merge in an X, some don't. Some merge with a center pipe connecting the two sides, some don't merge at all. What's the logic behind the different methods?
That is a great question and you also answered the question as well. The difference really comes in the flow of the exhausts gasses that cause the differences in gains. We normally test multiple different exhaust for the best sound and performance combination.
That is a great question and you also answered the question as well. The difference really comes in the flow of the exhausts gasses that cause the differences in gains. We normally test multiple different exhaust for the best sound and performance combination.
So how does one know—as a consumer—which method will decrease power? Nobody has publicly released before/after dyno charts of just a center section bypass. The last thing anybody wants to do is put on a center bypass, thinking it will have no effect on power—just a sound change—only to find that thousands of dollars later, it's actually retarded performance.
So how does one know—as a consumer—which method will decrease power? Nobody has publicly released before/after dyno charts of just a center section bypass. The last thing anybody wants to do is put on a center bypass, thinking it will have no effect on power—just a sound change—only to find that thousands of dollars later, it's actually retarded performance.
As someone who's just about to sink a not insignificant sum into a bypass, I'm curious too... Might reach out to the company and ask if they have before and after dyno numbers.
As someone who's just about to sink not an insignificant sum into a bypass, I'm curious too... Might reach out to the company and ask if they have before and after dyno numbers.
what's the point? dynos are too easy to manipulate. go with the one you like and the Company you trust, and then maybe you can do a before and after dyno for the benefit of those that may follow you.
what's the point? dynos are too easy to manipulate. go with the one you like and the Company you trust, and then maybe you can do a before and after dyno for the benefit of those that may follow you.
That sounds like a plan, will fit it after break-in period. Car arrives in a month.
So how does one know—as a consumer—which method will decrease power? Nobody has publicly released before/after dyno charts of just a center section bypass. The last thing anybody wants to do is put on a center bypass, thinking it will have no effect on power—just a sound change—only to find that thousands of dollars later, it's actually retarded performance.
There are so many variables that can affect the exhaust flow, there is not any general rule I can give you to help tell which Center Muffler Bypass configuration is best. What I can tell you is that we repeatedly Dyno Test our products throughout the development phase, and after testing various product designs, this design is the only one that was able to keep up the best performance while achieving that aggressive exhaust note we are looking for.
While on the original 997 GT3 we saw slight gains, the newer models had improved in many areas and our new focus in development became achieving the same sound while avoiding any noticeable power decreases. After testing various different designs, we concluded that a very similar design to our 997 version was still the best option. It helped us achieve that aggressive exhaust tone and weight savings, while keeping power loss to a negligible level.
If power is a priority, we would recommend headers and side muffler bypasses. You drop more weight and save the valves in the center muffler, that way you can switch the exhaust from quieter to louder whenever you want. Both provide significant weight savings but the side muffler bypasses drop 34 lbs. compared to the OEM parts, while the center muffler bypass drops 10 lbs. compared to the OEM. We chose to use Helical Valves on our 991 GT3 / GT3 RS side muffler bypasses for their unprecedented quality - which have been proven by many OEM manufacturers such as McLaren, Ferrari, Lamborghini, and many more. Helical valves are an integral part of our Side Muffler Bypass pipes, opening and closing with precision to control the gas flow and optimizing engine back-pressure for improved performance. This is an added performance benefit of the Side Muffler Bypass that the Center Muffler Bypass cannot provide.
Originally Posted by Alan C.
I thought you guys didn't think 321SS was worth the cost and polished everything. What changed?
We use T304 stainless steel currently, which is considered the highest grade to use for exhaust purposes for a variety of reasons from its physical strength to its resistance to corrosion. As our technology and infrastructure improve, we are always looking for ways we can improve as a company and stay at the forefront of the industry.
We are trying out 321 SS specifically for our GT3 Longtube Race Headers. We have not fabricated any using this material yet but we will be experimenting later in the summer and the benefits it provides, paying particular attention to its ability to resist heat at extremely high temperatures, which is the feature we are most curious about.
06-20-2018, 11:27 AM
The best Exhaust for a GT3
