Porsche 981 Cayman GT4 Fabspeed GT420 STREET Performance Package (2015-2016)

$9,595.95 - $9,795.95
(3 reviews) Write a Review
HP (whp):
TQ (ft/lbs):
WT (lbs):
  • Adjustable slip-on outlets for the Fabspeed GT4 Valvetronic Exhaust System which re-direct and control the exhaust volume by over 5dB; perfect for decibel-limited motorsport venues!

Why We Choose HJS Catalytic Converters: 

HJS German imported catalytic converters are made from some of the highest grade materials you can find in a catalytic converter. This yields high performance gains and longevity so it wont deteriorate over time like lower grade catalytic converters. These catalytic converters flow up to 93-95% of a straight pipe in most applications. The benefit is that you get the "straight pipe sound" while still being able to provide enough emissions scrubbing to prevent a check engine light.    

Fabspeed's GT420 STREET Performance Package is the premium solution to adding performance to your GT4 / Spyder on the street. Delivering over 400 horsepower to the crank with easy-to-install bolt-on upgrades, there is no better option for the GT4 owner seeking maximum power and performance while retaining catalysts. No need to swap engines or suffer long periods of downtime during a full engine re-build. Simply install the Fabspeed GT420 Package and begin outperforming the 911 Carrera GTS the very next day!                      


gt4-vt.jpg   Porsche Cayman GT4 Valvetronic Exhaust System
untitled-8.jpg   Porsche Cayman GT4 Sport Headers
gt4-ipe.jpg   Porsche Cayman GT4 IPD Competition Plenum Package
gt4-fil.jpg   Porsche Cayman GT4 BMC F1 Replacement Air Filters

gt4-ap.jpg   Porsche Cayman GT4 Cobb Accessport Tuner with GT420 ExperTune


  • Fits all Porsche 981 Cayman GT4 / Spyder models (2015-2016)

  • Instantly eliminates all symptoms of Carrera envy

  • Side effects may include extreme euphoria and uncontrollable excitement. In some cases, users have experienced acceleration-induced tunnel vision

  • Fabspeed's GT420 Street Performance Package added over 44 whp and 48 ft/lbs of low-end torque at 4283 RPM on a Spyder

  • Peak power was raised by 25 whp and 17 ft/lbs of torque - leaving the building with 363 whp and 316 ft/lbs of torque

  • All parts are easily installed with no cutting or welding required, bolt on and go

  • Optimized for maximum performance with NO check engine light, guaranteed

  • Choose between real matte Carbon Fiber tips or Single Wall Stainless Tips that are made in house for a racecar look

  • The Cobb Accessport gives you easy control over tuning your GT4, we send all documentation for uploading the GT420 flash to your vehicle upon purchasing

  • All Fabspeed performance products are backed by the Fabspeed Lifetime Warranty


To ensure proper header seal, after initial heat cycle, tighten all exhaust bolts to the OEM torque specs.


This product removes the OEM catalytic converters from the vehicle, and as such, is strictly intended for closed track events and off-road use only. This product contains a High-Flow Sport Catalytic Converter solely intended for track and race cars as it is NOT California Air Resources Board Certified and not EPA certified. You are hereby informed and warned to check your local, state, and federals laws before buying and installing these or any aftermarket parts to be sure whether usage is in violation. All installation-risk and use-risk is borne by the end-user and installer of these parts.


HP (whp):
TQ (ft/lbs):
WT (lbs):

3 Reviews

  • 5
    she's totally bitchin!!!

    Posted by Len on 21st Feb 2017

    Ya'll did an AWESOME job! She really sounds AND looks great! Those stainless tips are fabulous! I could not be happier! The Fabspeed valvetronic exhaust with the sport headers are absolutely THE way to go on the GT4. No question. I love being able to tone her down with the push of a button. Makes it easier to bring her quietly back into the neighborhood without shaking the windows....and when it's time to cut loose, the exhaust note is right there, perfect! PLEASE let everyone there at Fabspeed know that ya'll did a wonderful job on my GT4. I'm extremely grateful and PROUD to have another fine Fabspeed package on my new GT4.

  • 5
    LOVE IT!

    Posted by Lonnie C. on 8th Dec 2016

    I absolutely LOVE hitting the sport exhaust button on the GT4 and hearing that flat six REALLY sing like she's supposed to...all good with the Fabspeed exhaust system....from the headers to the cats, mufflers, pipes and tips. The performance gains and hearing her sing is ABSOLUTELY AWESOME!!! Worth every penny! NO GT4 is complete without it. Period. End of Story! THANKS again for all your help and a big THANKS to FABSPEED for such EXCELLENT PRODUCTS!

  • 5
    Had the Fabspeed GT420 Installed in the Spyder...

    Posted by George D. on 8th Dec 2016

    Rolled into Fabspeed at around 7:30 Wednesday morning to install the GT420 package consisting of the IPD plenum, 82mm throttle body, BMC filters, Fabspeed's catted sport headers, Valvetronic exhaust and custom tune. Upon arrival I was greeted by the gracious John Gaydos and given a full tour of the facility. Without seeing everything in full swing, there's no way to appreciate the attention to detail involved in the fabrication of Fabspeed components. The whole facility and associated equipment is state of the art. We started the day by getting a baseline reading of the car on the dyno. I know not to worry about the numbers as much as the change in the curve pre/post modification. Nonetheless, the car started the day at 337hp/299 lb-ft on the Dynojet. Luckily, we'd be able to compare numbers on the same dyno on the same day to appreciate the gains that would be achieved with the upgrades. At this point I was still questioning whether I had made the right choice going with the catted sport headers over the catless race headers. With everything in place it all ooks much tidier and streamlined. The only thing left to do was put the car back on the dyno and do the protune. Small problem, though - my car had the most recent Porsche firmware and Cobb hadn't written the program for it yet. This was at 5:30 pm and Fabspeed closes up for the day at 6. A call was put in to Cobb and they said they would get it done ASAP, which translated to about 2 hours. Clearly we weren't getting the tune done. Also, I had no way to get back to NJ. John didn't hesitate to give me the key to his Cayman R so I could get back home. I received a call this morning that Cobb came through and everything was up and running without a hitch. John brought the car back to me tonight and I had a little time to take it out for a spin. The car is much more responsive across the whole rev range. You can definitely feel that the torque dip has been addressed and the car feels very linear in the way it develops power. It sounds fantastic. No video truly captures how this system sounds. It has a very race-like quality to it. It doesn't make as much power up high as the race header setup, but it's still an improvement and the sound...oh, the sound is intoxicating in the higher revs. I don't regret going with the sport headers over the race headers. Volume-wise the sport headers/valvetronic has a lot of presence. The race headers would probably be way too loud for the street, especially with the top down. Performance wise, there's always a trade off - low end torque vs high end hp. I do tend to run my Porsches in the higher rev ranges even on the street but, again, the volume would be deafening with the catless headers. All in all, I'm very impressed with the system and the effort Fabspeed made. I wouldn't hesitate to call on them again for future projects.

Videos Hide Videos Show Videos