The option for the naturally-aspirated flat-six in the 718 model lineup was the first step toward recapturing Porsche’s signature sports car character, but there was more left to do. Porsche compromised to meet global regulations but driving purists couldn’t be blamed for wanting more.
With our experience in elevating the sound and performance character of Porsche sports cars, we had a road map available to make the most of this platform. It presented us with three opportunities to optimize the system, each of which plays a significant role in the overall sound and performance of the 718 Boxster or Cayman, whether upgraded individually or as a package. Those sections are the Headers, the Over Axle Pipes, and the Rear Muffler.
While Porsche’s pedigree leaves no doubt to the capabilities of their engineering, the limitations of aforementioned exhaust regulations make themselves very evident in the design of each section. The factory headers suffer from squashed primary tubing and an abrupt merge collector, feeding into a dense catalytic converter. These join to over axle pipes that are corked by heat-soaking particulate filter canisters, which are not monitored on North American cars thus making them a prime candidate for replacement. The over axle pipes split into two flow paths that meet a valved rear muffler, and that muffler is responsible for preserving a civilized temperament under cruising conditions, while encouraging an aggressive tone with valves open during spirited drives. While the valves-closed flow path is restrictive enough to retain a reasonable presence with upgraded headers or over axle pipes, the short and abrupt flow path of the valves-open condition results in a raw and potentially unsavory tone that is only amplified by changes made upstream. With two short bends out through the tips, thus no blending of the exhaust, the smooth, high-pitched sound of the previous generation of GT4/Spyder is lost to memory.
We took it upon ourselves as enthusiasts to explore how we could revitalize that platform for those looking to elevate their experience, either on the street or the track. When approaching this objective, we realized there are a number of goals that customers are looking to achieve and set out a road map accordingly.
Fortunately, optimizing a few key components can generate significant gains in multiple areas, providing cost-effective options to meet your goals. For drivers looking to elevate performance or sound level, upgrading the over axle pipes or headers will yield immediate results by ironing out the bottlenecks of the factory system.
Regardless of where you are in the world, the factory over axle pipes present a major cork in the flow of the exhaust system. A bulging particulate filter canister is monitored for European market vehicles but not for those in North America, yet they are present in all cars. That means in the American market we can directly swap with none of the potential side effects as all monitored emissions systems remain intact, resulting in the best “bang for your buck” upgrade in the exhaust system. As a standalone product, our free-flowing 2.25-inch over axle pipes maximize the 4-liter’s existing sound and character with notable increases in volume with valves open. But when retaining the factory rear muffler, the restrictive valves-closed condition maintains nearly OEM levels of cruising comfort, providing a significant sound delta between valves open and closed. Our resonated over axle pipes can add an additional layer of comfort by combating drone, smoothing out the 4-liter’s tone, and reducing overall sound level. But for those who simply want the most from one upgrade, our competition version will deliver the most aggressive sound performance, especially when paired with our Valve Controller Kit to force open the valves through the entire rev range. The baked-in valve programming only fully opens in mid to high RPMs, even with Sport selected, so this combination serves to provide the most sound level possible from a single component change.
To potentially further amplify those results, we addressed the restrictive factory headers to break the dam right at the source. The OEM units house the cat core which is similar in density to those particulate filters in the over axle pipes, and the squashed tubing and merge collector further restrict the exhaust flow into the next stage of the system. Our Competition Headers tackle all of those obstacles at once, eliminating that cat core to draw out longer and smoother tubing into an optimized merge collector, while our Street Headers use the same theories but include a higher-flow catalytic converter for those planning to retain all emissions equipment. Individually, our headers remove an immediate roadblock from the exhaust path and elicit significant sound and performance improvements, along with better heat management and weight savings. But combined with over axle pipes, the driving experience compounds into something transformational.
While you can pick and choose your way to increases in sound level or performance, there’s only one choice to get back the high-pitched motorsports tone that Porsche’s best flat-sixes are known for. Replacing the rear muffler with an x-pipe that blends the exhaust for a rich, smooth tone is the ultimate sound transformation, whether or not any additional pieces are added upstream.
The other products in our portfolio for the 4-liter 718s serve to accentuate and amplify the existing sound profile of the car, but that can be unsavory to some. The aggressive nature of the valves-open flow path delivers a raw and unrefined sound, especially at low RPMs and even more so if headers and over axle pipes come into play.
Our rear exhaust systems employ longer and higher-diameter x-pipes to recreate that intoxicating tone in both our Race and Valved exhaust applications. Our non-valved Race system delivers that sound entirely unrestricted, yet is available with the drone canisters we developed for the GT4 RS to maintain civilized cabin presence. But for the ultimate in sound and weight savings, our non-resonated Race Exhaust makes no compromises.
But for drivers who don’t live at the race track and need to dial it back at a moment’s notice, our Valved Exhaust presents itself. Two flow paths individually use x-pipes to create a distinctly memorable sound character, but the entirety of the system works cooperatively to maximize the qualities that drivers crave.
The muffler for valves-closed driving is smaller than the factory unit, retaining more of a sound experience in that condition and still using an internal x-pipe to extract the higher-pitched tones. This will assist in reducing exterior sound level for situations that warrant it, like in neighborhoods or highly-policed locations. But at the press of a button, the Porsche 4.0 expresses the emotion it was marketed with. The valves-open path bypasses that muffler and blends through a 2.5-inch x-pipe for a proper sound that was left out at the factory. Enthusiasts can pair it with our Valve Controller Kit as it was intended for, and we’ve tailored the secondary path to use residual flow and repurpose it as a Helmholtz chamber and limit low-RPM drone. This may create some leftover resonance with the valves closed, but we fully expect most drivers to be enjoying it with the valves open.
Whether your goal is for sound level, character or performance, each component plays a pivotal role in crafting that experience, and combining products into our best-selling packages is what makes the most of the 718 4-liter platform. By mating our Competition Over Axle Pipes to our Valved Exhaust System, our Sport Package sees increases in every category as a comprehensive solution to the exhaust system. Topping off with a header replacement would amplify the downstream upgrades, thus leaving no stone unturned in the endless pursuit of driving excellence.
While many drivers are looking to enhance their daily or weekend drives with an exhaust upgrade, these enthusiast-focused high-performance variants of the 718 are particularly suited for track use and we expect many of them to be used as such. This is our passion and expertise. We wanted to make sure our solutions were engineered to endure the most demanding environments, as long as the driver is too.
Instant benefits will come from an over axle pipe replacement, eliminating a significant source of heat which will net performance benefits as well as long-term protection of the components nearby. Removal of the factory particulate filter will generate significantly less radiant heat through and around the over axle pipes, and additional thermal protection measures are available through us. Of course, that’s not to mention the weight savings (nearly 11 lbs) and power gains from the highly-optimized 2.25-inch piece. But for the ultimate solution to sound and performance, and considerations of very little else, our full 2.5-inch headers-back Race Exhaust maximizes every inch to deliver on all the promises Porsche’s GT department made about the 4-liter 718.
But not everyone is looking to transform what is obviously a well-engineered driving experience. For some, the little things bring pleasure and tailor the sound just the way they like it. On the 718 models, this can be achieved by deleting the sound symposer. This vibrating diaphragm pumps through the firewall in Sport modes to provide sound presence that is especially beneficial in cars that may be limited by regulations. But that sound may not mix well with exhaust upgrades, and even in normal driving modes it can have some residual resonance. Our Sound Symposer Delete system removes that tube and plugs both sides of the mechanism to filter sound back to what you want to hear—especially if you’ve invested in upgrades elsewhere!
At the end of the day, achieving the ideal sound solution for your needs is about understanding what role each component in the system plays, and how they interact with each other. It can be a simple one-and-done to hone in on making it just right, or a completely transformational upgrade to character and performance. We’re here every step of the way to help you understand and get the most excitement and satisfaction from your 4-liter Porsche 718.
Give us a call to find what those options are for you!
