Pre-preg carbon fiber GT4 RS style hood on a manual GT4: the build Porsche won't sell

A GT4 RS style hood replicates one of the best details on Porsche's 718 Cayman GT4 RS: a gorgeous carbon fiber hood with two NACA ducts that cool its massive 408 mm front brakes (410 mm with the ceramic composite option). Owners on Porsche forums quote $11,500 to $19,000 for the genuine Porsche hood; the FYBR Aerodynamics dry carbon alternative costs a fraction of that.

FYBR Aerodynamics is E3Tuning's in-house carbon fiber brand.

The FYBR Aerodynamics GT4 RS style hood is a pre-preg dry carbon aftermarket upgrade (the pinnacle of carbon fiber manufacturing, creating the lightest and strongest carbon fiber parts in the process). It also recreates the two NACA ducts from the genuine GT4 RS. Out of the box those ducts are only cosmetic: nothing sits behind them, so they open straight into the front compartment. They can be made to work, though. The owner in this build did the conversion himself using genuine Porsche GT4 RS parts, and a hose test shows the ducts now empty at the front brakes.

YouTuber Matt Ross fitted our FYBR Aerodynamics pre-preg dry carbon GT4 RS style hood to his manual 718 Cayman GT4, then went further than the look: he installed genuine Porsche GT4 RS brake-duct parts so the ducts feed air to the front rotors. Here is the hood, the conversion and the part numbers, from his two build videos.

Matt bought his hood from us at a discount; the opinions, and the wrenching, are his own. Photos are stills from his videos, used with his permission.

Porsche builds the 718 Cayman GT4 RS with one transmission. In the words of Porsche's own press kit, the car is "exclusively available with the Porsche dual-clutch transmission (PDK)." Matt wanted the RS look and function with three pedals, so he started with a manual 2020 GT4 that insurance had totaled after a deer strike.

The factory aluminum hood came with the car dented and creased, and Matt figured aluminum would be harder to repair than steel.

Matt came in skeptical. "I can't say I've had the best experiences with aftermarket carbon fiber hoods in the past," he says, "but initial impressions are this thing is really, really nice. I mean, look at how even the V pattern meets in the middle."

That V is the weave: a 2x2 twill laid up as a mirror image, so the pattern meets at the center line of the hood, a feature in many of our FYBR Aerodynamics carbon fiber Porsche parts.

The real test was the swap. The hood reuses the original hinges and hardware, and Matt moved every factory part across from the old hood: "Every single part and piece transferred over without issue. No modifications, everything snapped and bolted into place perfectly. It's like an OEM carbon fiber hood."

He is also upfront about why he did it. The stock aluminum hood "is pretty darn light itself," he points out, so this was about style, and about replacing a damaged panel, not about weight.

His verdict once it was on the car: "Definitely the nicest carbon fiber hood I've ever purchased."

On the genuine GT4 RS, the hood's two NACA ducts feed air to the front brakes, whose 408 mm discs are 28 mm larger than the GT4's 380 mm discs. In Porsche's GT4 RS press kit, "two NACA air intakes in the bonnet direct air flow to the front wheels," and they "improve brake cooling but without impairing the drag coefficient of the vehicle."

A NACA duct is a low, recessed inlet first developed by the National Advisory Committee for Aeronautics, NASA's predecessor. It draws air in without a scoop sticking up into the airflow, which is why race cars use them.

Fit a GT4 RS style hood to a car without the RS ducting, and the ducts are exactly that: openings.

Matt's hose test showed why that matters. Water poured over the hood ran straight through the ducts and into the front compartment.

Matt worked from an owner's forum guide and bought the genuine Porsche GT4 RS brake-duct parts. Owners have also documented the same retrofit in detail on Rennlist. The job, in order:

• Swap the vent line Porsche's GT4 RS uses a different charcoal-canister vent line with a 90° bend, shaped to clear the path the new duct takes. Matt removed a cabin air filter to reach it.
• Fit the air guides Genuine GT4 RS air guides mount beside each front brake rotor. They carry an extra mounting point the GT4 part lacks, so Matt added a rivet nut to the body for it.
• Route the ducts through the wheel-well liners Porsche's GT4 RS uses different liners. Matt cut holes in his stock ones instead; the duct passes through at an angle, so the hole ends up larger than the duct itself.
• Trim the battery cover The cover under the hood has to be cut for the two ducts. Matt greased the duct seals, closed the hood to print an outline onto the cover, and cut to the line. Rubber seals then clamp the cover between the duct and the hood.
• Swap push pins for bolts At full steering lock, a plastic push pin touched Matt's aftermarket wheel. He replaced the pins with bolts, nuts, washers and thread locker, which he says look cleaner and hold better.

The genuine Porsche parts from Matt's list:

Left and right follow the owner's guide on Rennlist. Porsche revises part numbers over time (these air guides also appear with a -82 ending), so confirm every number for your car with a Porsche parts counter before ordering.

With everything in, Matt ran the same test. This time the water ran down the ducts and came out at the front brake rotors, in the wheel wells: the path Porsche designed the RS ducts to feed.

"It all came together really, really well," Matt says, "especially for an aftermarket hood and me not doing anything like this ever before."

Matt's build isn't finished. He has also bought our new dry carbon GT4 RS style fender conversion kit, so keep an eye on his channel for the install.

• The cuts are permanent The stock wheel-well liners and battery cover get cut. Porsche's GT4 RS versions of those parts exist if you would rather not cut, at extra cost.
• Confirm the parts for your car Matt thinks the conversion works on any 718, and possibly the 981, but he has only done it on his GT4. Check with a Porsche parts counter first.
• Consider sealing the cut edges Viewers suggested edging or grommets around the liner holes to keep road grime out of the wheel well area.
• Battery access takes more care The trimmed cover pieces have to line up and snap into place, so hooking up a battery tender is a little more work.
• Check wheel clearance With aggressive aftermarket wheels, turn to full lock and check that nothing touches, as Matt found with a push pin.
• Professional installation recommended The hood itself reuses the factory hinges and hardware. The duct conversion involves cutting, drilling and fuel-vapor plumbing, which is shop work for most owners.

2013-2025 Porsche Boxster & Cayman (981/982) / 2012-2019 Porsche 911 (991.1/991.2) GT4 RS Style Pre-Preg Dry Carbon Fiber Hood | FYBR Aerodynamics 2017-2025 Porsche 718 Cayman & Boxster (982) GT4 RS Style Dry Carbon Fiber Fender Conversion Kit [Liner Included] | FYBR Aerodynamics

Planning your own 718 build? Browse our Porsche 718 Boxster & Cayman (982) parts, or email info@e3tuning.com with your year and model and we'll help confirm fitment before you order.