SOUL Buyer’s Guide: Porsche 718 GT4 RS

Porsche’s RS models represent a lineage of uncompromising flagship performance, but this treatment was only ever offered to 911 models throughout history. Porsche slowly dialed up the performance on Boxster/Cayman models throughout the years but stopped short of a proper RS model until the market’s demand pushed them to go all-in.

The GT4 RS benefits significantly from Porsche’s GT and motorsports pedigree but its exhaust configuration is not a major deviation from the standard 4-liter models. For the sake of simplicity, it is still split into three sections: the headers, over axle pipes and the rear muffler. Like on the other 718s, each of these sections suffers from unavoidable regulatory constraints that we intended to sidestep.

Both the headers and over axle pipes are saddled with significant roadblocks to the detriment of sound and performance regardless of the market. Emissions equipment is stuffed into both sections to adhere to those regulations, and exhaust flow is compromised as a result of it. Whether your goals are focused on increasing power or sound, optimizing these sections will take immediate effect on those goals, and combining products will compound those effects for a simply transformational experience.

But targeting the over axle pipes first provides bang for the buck in both categories by ironing out the kinks of the factory components. Retaining the primary cat in the headers leaves the secondary cat open for replacement and the unmonitored particulate filter canister (in North American market) serves no purpose. Both our Competition and Resonated Over Axle Pipes prioritize unrestricted exhaust flow to generate immediate gains in performance and sound level with the valves open, with full 3-inch oval tubing delivering the optimal flow from the GT3-derived engine. The Resonated version provides a more modest volume change with a smoother tone while the Competition units offer the most aggressive increase in sound level from a single component change. Pairing with our Valve Controller Kit can override the factory PSE programming to unlock this sound throughout the rev range, or effectively mute it in environments in which it is necessary—like on sound-restrictive tracks or around your neighborhood. The factory programming only opens up fully at higher RPMs but our controller kit returns valve autonomy to the driver’s preference.

Meeting those same goals, or enhancing them even more, is the headers. For previous models, we’ve offered both “Street” and “Competition” variants to satisfy both road and track enthusiasts looking for additional sound and power. But owing to the increased demands of the GT4 RS’ engine, the compromises necessary to fit a catalytic converter into our header design would be more than we were comfortable with. So we made the decision to go forward with our optimal design to generate the greatest exhaust velocity possible, which delivers tangible power gains and an amplification of the downstream exhaust system.

But the GT4 RS is properly marketed from its motorsport lineage, and for drivers who want to capture that emotional purity, the rear muffler is either the starting point or the ending point. The factory unit is carried over from the standard GT4, therefore restricting tubing diameter and limiting flow from the RS’ high-output engine. But the muffler is effective in preserving cabin presence with the valves closed, even with upgraded headers or over axle pipes, while the open flow path quickly routes through the tips leaving the tone aggressive and unrefined.

Retaining that reasonable presence but reviving the motorsports character of the flat-six is a tall order that our research and development team toiled away on for weeks, but we’re confident in the results. Our Valved Exhaust System provides a meaningful sound level delta between the two modes, effectively transitioning from a smooth high-pitched tone to a comfortable cruising presence on demand. Extensive testing and an unwillingness to compromise made it possible, with full 3-inch oval x-pipes for both flow paths, and drone canisters fighting the excess resonance from the GT3 engine using the packaging space available—the latter resulting from an exhaustive testing process that returned significant improvement over early iterations. This labor-intensive build is multi-layered in how it interacts with the sound profile, with the valves open condition also benefiting from the secondary path’s Helmholtz properties and silencing drone even further. But due to the size and location of the drone canisters, the system must be paired with aftermarket over axle pipes—certainly on the board for those chasing overall sound enhancements.

But to prioritize the character and tone change of a muffler replacement and sidestep the intricacies of the Valved Exhaust System, our non-valved Race Exhaust is a cost-effective, lightweight, and emissions-compliant upgrade that still uses the same development and technology as the Valved Exhaust. The 3-inch oval x-pipe blends the exhaust for a high-pitched flat-six tone with attached anti-drone tubes to limit resonance at lower RPMs, again the result of chasing our goals through countless iterations. For a single component to deliver transformational sound, the Race Exhaust is impactful in giving the GT4 RS the sound worthy of its credentials.

While any single component can work to improve performance, sound level or sound quality, as each component functions in its own specific role, combining products together compounds the results for a dramatic sound experience. We’ve strategically curated a number of exhaust packages that pair integral components together to achieve multiple objectives at once or improve individual results exponentially.

Beginning upstream, we’ve logically paired our Competition Headers with our Sport Cat Over Axle Pipes to amplify sound and performance while still being considerate of emissions equipment. Our Sport Header Package matches unrestricted headers and high-flow catted over axle pipes, instantly eschewing the major compromises of the factory system and resulting in performance improvements that span the entire rev range while the factory muffler retains stock-like cabin presence with the valves closed.

But to capture that motorsports essence, our exhaust packages enhance the sound experience of both tone quality and volume, and the underlying performance benefits that come with it. Our non-valved Race Exhaust Package sheds 20 pounds from the factory components, opens up a full 3 inches of flow through the tips, with a bespoke x-pipe delivering that high-pitched tone and anti-drone tubes mitigating the unsavory resonance that is inherent to the GT4 RS’ engine. To further capitalize on the ultimate performance potential in conjunction with the signature sound, truly a no-compromise solution, adding headers with our Performance Package eliminates all of the factory system’s drawbacks. Whether your goals are for sound or power, this complete package leaves nothing in the way of achieving them.

Even though the GT4 RS represents the pinnacle of Porsche’s development for the road-going Cayman platform, it still suffers from the necessary bottlenecks that production cars are forced to confront. But for those who intend to realize everything that the GT4 RS is capable of in terms of sound or performance, our full suite of exhaust products has been developed to comprehensively achieve it.