Replacing the heavy and restrictive factory headers is central to improving performance. By pursuing a full system replacement we can eliminate the restrictive cat assemblies, the “particulate filters”, and the giant 7 ⅝ connection point to the factory rear muffler assembly. A simple flange optimization to our previous generation GT3 Competition Headers allows us to get rid of the factory 991 gen connection point requiring costly OEM clamps and donut gaskets and utilize a more efficient v-band connection point.
Even a premier engineering masterpiece like the GT3 comes from Porsche fitted with exhaust manifolds restricted in terms of primary tubing length, runner diameter, and merge collection efficiency due to dense catalytic converters, mass production, emissions and sound restriction compromises. By refining the interface between the flange/primary tubes, using smooth radius large diameter bends, and implementing performance oriented collectors with merge spikes, we have been able to achieve increased flow, response, and performance with a more aggressive exhaust note to match. A slip on merge collector was not considered to prevent any chances of exhaust leaks. Instead we focused on designing a high flow collector from CAD to CNC for a no compromise end result. This bespoke billet collector allows for maximized runner length and the elimination of several welds in the interest of durability. Our billet CNC head flanges allow for a more efficient transition from exhaust ports into the runners and adds extra strength in a high stress area preventing the chances for any cracking from repeated, hard use during track days.
REAR EXHAUST SECTION
With limited room under the vehicle we had to craft an intricate solution and loop the exhaust to keep the cats in line after the headers to maximize exhaust velocity. A muffler proved to be the most effective way to reduce the drone level under 3k rpm enough to meet our goals for reduced cabin presence for an exciting touring level of sound.
With valves open, exhaust is free to flow through 3” piping and an x-pipe that merges the exhaust flow for a higher pitched, smooth sound with maximum flow characteristics. With valves closed the exhaust is routed through secondary flow path piping and a bespoke SOUL muffler. The internal design has little to no restriction in the flow path, using straight-through perforated piping to allow exhaust gasses to escape and become muffled in the surrounding packing material of the muffler body. The muffler also incorporates an internal x-pipe to allow the exhaust flow to merge smoothly. All of these characteristics are crucial towards reducing and smoothing out the drone in the sub 3,000rpm range while enhancing the higher pitched note we were after in both the valves closed and open conditions.
In addition to the bespoke muffler design, there are several other unique characteristics we’ve brought into play on this system which revolve around the secondary flow path entering the muffler. The key thing to note here is that the valves open flow path is not limited to the external x-pipe flow path as some of the exhaust flow is still going through the secondary flow path even when the valves are open. This design is essentially utilizing the entire secondary flow path and muffler design to smooth out the tone and drone in valves open mode as well. Utilizing this secondary flow path for cruising cabin presence, we were able to go aggressive on the design of the primary valves open flow path to maximize the sound improvement without incorporating additional resonators or mufflers.
The catted/catless sections are interchangeable. You can reduce the chance of CELs with 200cell cats and tone down the exhaust if need be, or you can run the catless section to amp up the fun and performance on track. We also utilize a tip plate (same style as used on 991 GT3’s) allowing one to switch between tip assemblies/styles.
The exhaust valves on this car have electronic actuators mounted to a free moving mechanical valve body. Factory exhaust valve programming has the valves closed until 4k rpm, then gradually opening from 4k-5k rpm at which point they are then fully open. With PSE on you can rev the car with valves open but as soon as you accelerate they close again and this cycle repeats with the same functionality to 4k with the progressive opening to 5k. For those looking for full valve override so the valves are 100% open at wide open throttle regardless of rpm, ECU tuning is available to achieve this.
The valves on this platform have taken a notable amount of R&D as relocating or disconnecting them can cause check engine lights and performance issues. The actuators themselves are what keep the tension on the valve bodies, so you can’t take them off and have the valves default open via spring pressure like previous vacuum actuated OEM valves. The included hardware ensures proper valve operation and prevents any chance of issues.
In summary, this system was designed to offer a more desirable sound experience with tone enhancement under all conditions. Enjoy more presence during casual driving and an aggressive wail summoned by your right foot. The blending of banks from the X pipes combined with the sound attenuating features of the muffler gives the car a higher pitched sound befitting of a GT car with a respectable increase in mechanical tone and aggression.
- Very smooth experience in the cabin – from rolling on the gas at low rpm to high rpm WOT.
- Higher pitched and more refined in the low end than a system without muffler
- Comfortable under 4k rpms with a reasonable level of cabin presence/drone.
- Noticeable delta of sound level in and outside the car with the ability to fly under the radar with valves closed during casual driving.
- With valves closed, volume is increased by a refined amount. The sound is not only more pronounced, but smoother and more exciting with more tone than the dull, hollow factory exhaust note.
- Aggressive at wide open throttle when valves begin opening at 4k then fully open at 5k. A streetable, reasonable level of volume on command compared to a muffler-less system that is loud at all times.
CONSTRUCTION: Each system is assembled in the USA out of mandrel bent, thick wall .065″” T304L stainless steel. Our billet 304L stainless steel head flanges and merge collector are precision cut on a 5-axis CNC machine for the best possible exhaust flow and strength. Back purged TIG welding (with ARCAL™ Prime argon gas) ensures proper weld penetration and longevity – crucial for durability on the track. We fabricate the headers and system using thick gauge aluminum fixtures which act as a great heat sink during the welding process and prevent warping not only of our products, but the fixtures themselves to ensure perfect fitment.
CERAMIC COATING: Jet-Hot ceramic coating is available for specific configurations at an additional charge. Extreme (1300) or Ultra Extreme Heat (2500) coatings can lower surrounding temperatures by up to 65% and protect from thermal oxidation and corrosion. Please contact us for more information and a quote.
CHECK ENGINE LIGHT?: The catless Competition version may trigger a check engine light due to removal of factory catalytic converters. We suggest a custom ECU tune to disable any check engine lights (for track use only).
HJS HD 200 CELL CATALYSTS: The highest quality catalytic converters available, known for their industry leading flow and durability. They are efficient enough to meet strict EURO 4 emission standards while still allowing for an increase in flow. The HD design uses premium triple foil winding for maximum strength. The brazing stripe is an extra feature in the interest of durability – it prevents the core from moving or experiencing any damage from sustained high horsepower abuse.
BOLT ON AND GO: Every set is rigorously quality-checked prior to shipping and then foam packed to ensure your order arrives in perfect condition.
LIFETIME WARRANTY: Enjoy your SOUL exhaust components with confidence on both the street and track as they are covered for life! Our team will quickly work with you to resolve any issues or answer any questions that you may have. We cover our HJS catalytic converters with a 3 year warranty while the headers themselves are backed by our Lifetime Warranty.
+ This product is not CARB certified and may not be legal for use on emissions controlled vehicles; intended for closed course competition use only
+ United States based customers purchasing this product are required to sign our Catless Exhaust Component Waiver here.
We’ve got your back!
German Muscle takes “customer service” very personally. We understand that finding the right parts can be overwhelming. Education and awareness are the principles that keep us ahead of the curve. Let us make this experience simple, easy, and awesome, so without hesitation give us a call at (480) 569-3402, feel free to direct message on our live chat, or email us at email@example.com.
Make sure to follow us on Instagram: @GermanMuscleAZ