SKU: 38561465406

Fabspeed 981 Cayman GT4/Spyder Valvetronic GT3 Muffler Conversion Kit (FS.POR.981GT4.GT3CKBR)

Sale price$1246.02 Regular price$1384.47
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Ships within 48 hours · Estimated delivery Aug 17 - Aug 22

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Description

Fabspeed 981 Cayman GT4/Spyder Valvetronic GT3 Muffler Conversion Kit (FS.POR.981GT4.GT3CKBR)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

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 livable 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. 

FEATURES:

  • 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
  • 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

NOTE:

  • OEM GT3 center muffler is NOT included
Shipping Notes
  • Free Standard Shipping on $100+ Orders to the USA.
  • Except Preorder products are shipped in 48 hours.
  • Delivery to the USA:
  1. Standard Shipping : 3-10 business days
  • If time is of the essence, please consider selecting expedited delivery for faster service.
Exchange/Return Notes
  • We offer a 30-day return/exchange service after receiving.
  • Final sale items are not eligible for returns or exchanges.
  • To process your return/exchange, please contact us at [email protected]
  • Please click here for more details>>> Return & Exchange Policy
SKU: 38561465406

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4.5 ★★★★★
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Gail
Massapequa, US
★★★★★ 5
The answer to calloused feet.
Color: Pink & Beige, Size: Medium/Large(fits size 8 to 11)
If you have dry callused soles, these are your answer. All my calluses left and my feet were very soft. They should not be walked in unless you are very, very careful as you will slip and fall. I stopped using them for a while and all my problem calluses are back, even when I use lotion at night. They tell you not to sleep in them, I don't know why. I do put these on at night and end up taking them off later as they're not comfortable to sleep in.
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Reviewed in the United States on April 28, 2026
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Angela A Mathis
Birmingham, US
★★★★★ 5
Good Product
Color: Pink & Beige, Size: Medium/Large(fits size 8 to 11)
These socks are good for moistening. Durability is awesome Fit true to size. Traction could be a little better. The sock are very comfortable
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Reviewed in the United States on April 23, 2026
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Verified Purchase
Tj
Charlottesville, US
★★★★★ 4
Slippery when wet!!!
Color: Pink & Beige, Size: Medium/Large(fits size 8 to 11)
“These moisturizing slippers are actually really comfortable and feel great on the feet. They’re soft, cozy, and do help moisturize while you wear them. I also think they’re a good value for the money. The only downside is that once your feet get moisturized, they can get slippery inside the slippers, so I wouldn’t recommend walking around too much in them. Better for relaxing and letting your feet soak up the moisture than for being up and moving around.”
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Reviewed in the United States on May 26, 2026
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J. Randle
Battle Creek, US
★★★★★ 5
Love them
Color: Pink & Beige, Size: Medium/Large(fits size 8 to 11)
I wear a size 11.5 in ladies shoe and these just barely fit. Butttt after I put lotion on my feet and slipped these on and left them on for about 30 mins. It left my feet really soft! They work great as intended. Would buy again
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Reviewed in the United States on January 31, 2026
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Vonda Kioultzopoulos
Dallas, US
★★★★★ 3
Effective but may be uncomfortable
Color: Pink & Beige, Size: Medium/Large(fits size 8 to 11)
I have eczema on my feet and use a prescription cream that I leave on overnight. I often have a problem sleeping in socks but the silicone feels cool on my feet. The only drawback I have is the opening of the socks feel very tight around my ankles making them uncomfortable on me. I wish the opening was a bit more flexible.
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Reviewed in the United States on September 20, 2025

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