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Valved GT3 Muffler Conversion Kit

A conversion kit that lets 6-speed manual Porsche 981 Cayman GT4 and Boxster Spyder owners (2015-2016) fit a Porsche OEM 991 GT3-style center muffler, or Fabspeed's own GT3-spec muffler options, in place of the factory GT4 unit. It's built around 2.5-inch CNC mandrel-bent left and right over-axle pipes and valved side muffler inlet Y-pipes that retain the factory PSE valve function, using the same Helical UK aerospace-grade exhaust valves Porsche fits to GT3 cars. Since the 991 GT3 muffler was engineered to support 475 hp versus the 981 GT4 muffler's 385 hp design limit, it flows noticeably better, and with PSE off the exhaust stays tame in the cabin while opening up to a flat-six howl with PSE on. The OEM GT3 center muffler itself is not included, and a PDK version of this kit isn't yet available.
Frequently asked
Which cars does the Valved GT3 Muffler Conversion Kit fit?
Fits your 981 Boxster Spyder. Fabspeed lists this piece for: 6 speed manual Porsche 981 Cayman GT4 / 981 Boxster Spyder (2015-2016). Exact fitment for your year, trim and options is confirmed on your free consult before anything is ordered.
What does the price include?
The delivered price includes the part from Fabspeed USA, freight to Australia, import costs and GST. Enter your postcode to refine delivery; the final figure is confirmed on consult.
How long until it arrives?
Every Fabspeed part is made in-house at Fabspeed USA with about a one-week production lead time, then allow another 3-4 days for delivery to Australia via UPS. That freight is already included in the price.
Does this include the GT3 muffler itself?
No, the OEM GT3 center muffler is not included; Fabspeed recommends its own GT3 center muffler as a bullet-proof alternative.
Will this work with a PDK gearbox?
Not yet. This kit currently fits 6-speed manual cars only; a PDK version will be available once fitment has been tested.
Why does this flow better than the stock GT4 muffler?
The 991 GT3 muffler was engineered by Porsche to support 475 hp, well beyond the 981 GT4 muffler's 385 hp design limit, so it flows more freely.
Which option should I choose?
Choose a Fabspeed tip finish (Carbon Fiber, Satin Black, Polished or Brushed Stainless, Titanium) to match your car's look, or select Re-use OEM Tips to keep your existing factory tips, since this kit is also designed to accept factory 997 through 991 GT3 tips directly.
Who installs it?
Rennen Motorsport in Adelaide, or an authorised dealer near you. Fitting it yourself may also be an option depending on the part, so raise it on your consult; professional installation is quoted separately.
Is it covered by warranty?
Fabspeed products carry the manufacturer's warranty, supported locally through Rennen Plus as the Australian principal. See our returns policy.
Can I just buy this outright, or do I need to talk to someone first?
Every enquiry, whether it's one part or a full build, starts with a free consult. We confirm the exact spec for your car before anything is quoted or ordered.
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