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Discussion Starter #1 (Edited)
We've had the ultimate pleasure of an extended development term with the mighty GT4. Many on the team here agree, this is the perfect drivers’ car. It's utterly brilliant as is... but we'd like to refine it even further.




We set our engineers and tuner on the GT4 immediately and have tested many combinations of exhaust components. Our first course: catless Race Headers and HJS HD 200-cell high flow catalyst equipped Sport Headers. Unlock significant power and aggressive sound with Fabspeed Motorsport.




POWER- Real wheel gains from our Dynojet


RACE HEADERS: Power, power everywhere. Our precision-engineered Race Headers add up to 18 horsepower at the wheels and 15 ft/lbs of torque at 6300 RPM, increasing the already impressive performance of the Porsche GT4. Down low they give you a kick in the pants, adding 27 whp and 38 ft/lbs of torque at 3700 RPM to really help you claw out of the corners with reckless abandon. Significant gains are found throughout the entire powerband, especially at higher RPM which makes these perfect for track use. 911 owners: You’ve just been put on notice!




SPORT HEADERS: The HJS HD 200-cell catalysts get the (emissions) job done while still unlocking impressive gains. Overall gains are not as abundant as the Race Header but you'll really notice the great increase in low-end pull from the added 39 ft/lbs of torque at 3600 RPM!




SOUND: You hear the GT4 coming and you know something unique is upon you. The Race Headers accentuate the rawness of the 3.8L engine and broadcast it aggressively. Driving around with valves open will elicit head turns, neck snaps, and smiles from anyone with a soul in a quarter mile radius; the car emanates a race car presence inside and out. You can't help but smile with every autoblip downshift as the car lets out its war cry. Overall cabin volume is louder, yet droning is not unbearably harsh with valves open given the race-like nature of this performance product. Close the valves, and you could drive every day.


The Sport Headers, due to the catalysts, offer a slightly smoother sound with a moderate volume increase over stock. It's a perfect upgrade with no compromises.


As you'll hear, the GT4 sounds incredible equipped with both Fabspeed Race and Sport Headers.



CHECK ENGINE LIGHTS: In over 200 miles of testing, our development vehicle did NOT trigger a CEL, even with the catless Race Headers.


WEIGHT: Shed 6lbs with Sport Headers and 10lbs with Race Headers.


CONSTRUCTION: Each header is precision-machined using our state-of-the art Unison CNC electric mandrel bender, Haas CNC machines, and hand TIG-welded by our passionate and experienced fabricators. As always, we invite you to come by our shop and showroom for a full tour where you can see our exhaust systems being fabricated first-hand.





Our headers are currently in-stock and ready to ship. More GT4 products are also in the pipeline, so stay tuned. You can see full information and pricing on all our GT4 offerings here or message me at any time for discounted forum member pricing and insider info.​
 

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hi mate... i love your products...used them on my previous 964.... but now i have a question.... why only 6300 rpm on the dyno chart? what about the top end ? thanks in advance
 
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Discussion Starter #3
Hello!

Thank you very much for the kind words and your loyalty to the brand :) From viewing these dynographs I am seeing readings up to at least 6900rpm. If you are referring to one of the three vertical lines on graph, in particular the one of the Sport Headers at 6500rpm and Race Headers at 6300rpm, it is used to measure the delta between the stock and modified results to calculate the performance gains. We chose those particular RPM points as this is where we achieved our maximum "peak horsepower" gains as that is one of the common comparisons between model vehicles and performance products. We also chose to show our overall maximum performance gains at two other areas in the powercurve to give a great representation of the cumulative performance transformation felt while running through the gears.
 
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Discussion Starter #6 (Edited)
Thanks for putting up the dyno graphs, always interesting to see! congrats on the killer torque gain down low very impressive!
Thank you Mike :) How are you enjoying the new exhaust tips? We're not done extracting power just yet, stay tuned for more information on our exhaust!

Are there secondary cats downstream from the headers? How is it possible that the race headers don't trigger a CEL?
There are no secondary cats downstream from the headers on the GT4. In regards to the check engine light I can only say we have put 200+ miles on the vehicle and have had no CEL. Our theory is that Porsche may have desensitized the O2 monitoring system as the GT4s are built with track use in mind....or VW designed the monitoring system ;)

I've attached a picture of the factory exhaust system so all can see. We'll post another comparison with our future system.
 

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Hello!

Thank you very much for the kind words and your loyalty to the brand :) From viewing these dynographs I am seeing readings up to at least 6900rpm. If you are referring to one of the three vertical lines on graph, in particular the one of the Sport Headers at 6500rpm and Race Headers at 6300rpm, it is used to measure the delta between the stock and modified results to calculate the performance gains. We chose those particular RPM points as this is where we achieved our maximum "peak horsepower" gains as that is one of the common comparisons between model vehicles and performance products. We also chose to show our overall maximum performance gains at two other areas in the powercurve to give a great representation of the cumulative performance transformation felt while running through the gears.
Great work guys! The headers look awesome and are much needed for the GT4. I do have the same question though why does the dyno graph stop at around 6900?? Why not take the car up to its redline? I would be interested to see how the headers impact the mid-top-end torque dip that occurs around 6800rpm.
 
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Discussion Starter #8
Great work guys! The headers look awesome and are much needed for the GT4. I do have the same question though why does the dyno graph stop at around 6900?? Why not take the car up to its redline? I would be interested to see how the headers impact the mid-top-end torque dip that occurs around 6800rpm.
Thank you very much! We did rev the car out higher but as seen the gains start to taper down. The GT4 was delivered directly to us, fresh with plastics. Until we had put more miles on the car we did not want to abuse it out of respect to the owner. In all future dyno runs we will run the car out to redline.
 

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headers and filters just landed in Italy....i will let you know asap....:cheers:
Subbed! I'm possibly interested in filters and headers as well.
 
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latest news... found the manifolds in the fedex box but no filters... fabspeed told me that the filters are not available and they will ship asap....
scheduled a dyno at Autech for the next saturday (chassis dyno)...
so i will have for the first time (never done before on my old cars) before and post dynochart....
 
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Discussion Starter #16 (Edited)
Subbed! I'm possibly interested in filters and headers as well.
Looking forward to working with you BJ. The GT4 has such amazing potential, you are going to love the results! Give me a call when you have a chance and we can go over the details :)


We are looking forward to the dyno results and your thoughts of the system after installation. Get ready to spend a lot more time behind the wheel, the sound is intoxicating haha
 

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just finished the headers installation.... it took about 3 hours.... some minor problems with the oem studs that fit on the head side... there is so little space for the correct installation and proper tightening ....so we installed some aftermarket studs found in my buddy workshop.....
we removed some bits that are not necessary and made some little modifications for the o2 sensor cables correct position.....
we used the old oem gaskets that were still perfect and a lot better than the ones provided with the headers...
i did not rev to redline this night... but i can say, at the moment, that the sound improvement is fantastic... a bit more bangs and burbles.... and a more aggressive sound at the higher revs.... not in the 7000 rpm area at the moment.....
anyway i'm very very happy with my purchase...

"studs problem"
 

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.... I forgot to mention .... the size and structure of fab headers are a world apart from oem ones.... as you can see from the photos below .... the inlets and tube dimensions are dramatically larger .... so I hope in good improvement in performance ....
 
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