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Fabspeed Porsche 981 Cayman GT4 / Spyder Valvetronic GT3 Muffler Conversion Kit

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€1.640,87 - €2.068,36
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Fabspeed Porsche 981 Cayman GT4 / Spyder Valvetronic GT3 Muffler Conversion Kit

€1.640,87 - €2.068,36

Fabspeed Porsche 981 Cayman GT4 / Spyder Valvetronic GT3 Muffler Conversion Kit

€1.640,87 - €2.068,36

Porsche Boxster Cayman owners have requested a conversion kit that allows the installation of a Porsche OEM 991 GT3 center muffler onto their cars. Fabspeed Motorsport listened and designed in CAD and built inhouse a lightweight installation kit that allows any 6 speed Porsche 981 GT4 or Spyder owner to install an OEM GT3 center muffler (A PDK version will also be available once we are able to test fitment). This kit also allows the installation of a Fabspeed 991 GT3 Center Muffler Bypass Pipe or 991 GT3 Center Mini Maxflo Performance Exhaust onto your 981 GT4/Spyder.

The system consists of 2.5" 63.5mm CNC mandrel bent one piece Left and Right side over axle pipes and clamps. Then a set of valved side muffler inlet Y-pipes that retain the factory PSE valved exhaust functionality. The valves are OEM Porsche GT3 HELICAL vacuum-actuated exhaust valves that are imported from the U.K. We use our FLOW Waterjet to cut a CAD designed, lightweight, stainless steel mounting bracket to hold the muffler; hardware for installation is included. This and the Factory Porsche muffler band straps hold everything in place. For tips, you can use the factory 991 GT3 tips or you can order our custom exhaust tip mount with any choice of our signature tips.

SOUND: Enjoy the characteristic sound of a factory Porsche engineered exhaust but with a nice increase in volume! With PSE off (valves closed), the exhaust is still tame and liveable in the cabin. However, with PSE on (valves open) hear that flat 6 howl up to redline! The larger over axle pipes that are included also contribute to the overall louder tone.

POWER: The 991 GT3 muffler was designed by Porsche to support 475 HP, because of this it flows a lot better than the 981 GT4 muffler that was only designed for 385 HP. We expect this increase in flow, helped by our larger over axle pipes and muffler inlets, to give a nice HP increase. 

FINISH: Full #2 polished T304L stainless steel, beautifully welded together, and finished off with your choice of premium Fabspeed tips or use the OEM 991 GT3 tips.


  • Fits all 6 speed manual Porsche 981 Cayman GT4 / 981 Boxster Spyder vehicles (2015-2016). A PDK version will also be available once we are able to test fitment
  • Choose between your choice of Premium Fabspeed Exhaust Tips or use OEM 991 GT3 Tips.
  • CNC Mandrel bent 2.5" 63.5 precision over axle pipes to valvetronic inlet pipes
  • Flow WaterJet cut muffler mounting bracket
  • Innovation, not Imitation. 
  • Helical Aerospace United Kingdom exhaust valves- same OEM quality valves used on Porsche GT3, GT3RS. Made with Silica carbide.
  • Constructed from 14-16ga T304L stainless steel tubing for maximum power and durability
  • Direct bolt-on installation; no cutting or welding required
  • All Fabspeed performance products are backed by the Fabspeed Lifetime Warranty


  • OEM GT3 center muffler is NOT included

Returns Policy

You may return most new, unopened items within 30 days of delivery for a full refund. We'll also pay the return shipping costs if the return is a result of our error (you received an incorrect or defective item, etc.).

You should expect to receive your refund within four weeks of giving your package to the return shipper, however, in many cases you will receive a refund more quickly. This time period includes the transit time for us to receive your return from the shipper (5 to 10 business days), the time it takes us to process your return once we receive it (3 to 5 business days), and the time it takes your bank to process our refund request (5 to 10 business days).

If you need to return an item, simply login to your account, view the order using the "Complete Orders" link under the My Account menu and click the Return Item(s) button. We'll notify you via e-mail of your refund once we've received and processed the returned item.


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Please also note that the shipping rates for many items we sell are weight-based. The weight of any such item can be found on its detail page. To reflect the policies of the shipping companies we use, all weights will be rounded up to the next full pound.

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