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SOUL DEVELOPMENT: 991.1 Carrera Valved Performance Exhaust – IMPROVED!
You may have noticed that we’ve discontinued our 991.1 Carrera Valved Exhaust and a new system is available in its place. We’d like to share the development process behind our new and improved Valved Performance Exhaust System!
Resonators can reduce annoying drone and provide a smoother exhaust note without sacrificing volume and aggression. While the resonators we used were effective – we wanted to keep the aggression of the exhaust but refine it to have even less drone and in cabin intrusion. Effectively, our aim was to refine the level of daily driving comfort without sacrificing the race inspired tone and straight-through exhaust design. A larger resonator would not yield the results we are looking for while requiring some revisions for clearances – this could compromise the high flow design principles of our exhaust. Another thing to consider is that adding higher flowing aftermarket headers – like our Long Tube Street Headers – to an aggressive rear system without proper sound attenuating features could result in a overly loud, possibly unpleasant driving experience. Nearly 40% of our customers paired their rear exhaust with upgraded headers making it imperative that we consider such a configuration and engineer the exhaust appropriately. We set out to experiment with both factory and aftermarket headers to find the perfect recipe.
Helmholtz resonators (also known as anti-drone tubes) are an effective way to reduce undesirable frequencies when engineered and utilized correctly. We have years of experience incorporating them into our exhaust systems, such as our 996-997 Turbo Competition Exhausts (pictured below) to cut down on the in-cabin presence that is well known to arise in these vehicles with modified exhausts.
Through calculations on factors such as number of cylinders, target RPM, and other factors (Sorry – SOUL Secret Recipe ) you can determine the appropriate volume necessary to create the Helmholtz resonator. The 991.1 Carrera has an inherent 3,000-3,500 RPM range where drone can present itself when you add higher flowing exhaust components. Our goal was to filter out the undesirable frequencies in that range while smoothing the valves closed to open transition on factory PSE equipped cars.
Back to the R&D table. We had fixtured a stock center muffler to define the area in which we can work, mounting points, and any design restrictions. With our calculations in place, it was time to craft a system and start experimenting with the Helmholtz resonators to get the sound we are looking for.
We began working on the first version of our design. Each system is TIG welded together in a heavy gauge aluminum fixture. Why aluminum? Although it’s more expensive it prevents any potential warping over the life of the fixture – steel can warp over time causing possible fitment issues in the future. This ensures our products fit perfectly every time.
We completed the prototype system and mounted it to the vehicle – with and without our catted headers. The exhaust sound was improved and drone mitigated to a noticeable extent – but where some may stop and call it a success, we wanted to do further testing to get the best possible results for our customers. Slight changes were made for Prototype 2 to test the effectiveness of not only the calculations, but the placement of the tubes themselves.
While we were installing the second prototype – we noticed the inner shell on the primary exhaust tip is held on by three small spot welds. Removing this inner tip section effectively increases the inner tip diameter from 1.5″ to 2.5″ to match the 2.5″ outlets of our exhaust perfectly for maximum flow! You simply grind down three small spot welds and the inner shell comes right out.
We highly recommend this modification when using your factory tips with our Valved Performance Exhaust for the greatest efficiency, we’ll even do it for you! Alternatively we will be offering both polished chrome and black chrome tips to achieve the same effect.
For the final prototype we relocated the anti-drone tubes to the exhaust inlets, right off the main pipes instead of the T’ed off design shown above. This design has proved to offer the very best results on this application and achieved our high standards for sound quality and drivability. The math can be done to create the Helmholtz resonators – but how you incorporate them into your design makes a big difference.
The sound is aggressive – a primary benefit of our system is that with valves open there is straight, unrestricted path from the 2.5″ piping to the tips – but we’ve effectively massaged extra refinement into the system to match the premium experience that embodies all things Porsche. With valves both open and closed the X-pipe helps smooth the sound even further. All in all, we’re very happy with the results and we’re sure you will be too!
Now it’s time to wrap up development and start production.
Mandrel bent piping is cut to fit into cast templates – you can see us working on a template here. This allows the fabricator to “kit” the pieces necessary prior to welding.
Here is Max building a system for our first production run. Back purged welds ensure proper penetration and exhaust longevity.
Our proprietary blasted finish not only looks great but reveals any imperfections such as pinholes in welds that are normally hard to detect on raw or polished stainless steel. This along with our back purged welds results in the best possible product and longevity. It also allows us to refinish at any time should you want your exhaust parts freshened up.
Before each system ships we do a final inspection for fit and finish then securely pack it up with hardware, installation guide, and a microfiber towel to wipe any debris off from installation. Expanding foam ensures even coverage all around each component to prevent any potential for damage in shipping. It’s time consuming and expensive, but our mission is to have a perfect product in your hands every time!
Thank you for reading our development post! We’d be happy to answer any questions that you have or point you to your nearest SOUL dealer and installer for a system of your own!
MSRP: $2,895 - reuse factory tips - $3,295 with Polished Chrome Tips - $3,445 with Black Chrome Tips - Add $100 for valve controller kit to have total control over valves
sales@soulpp.com / 855-486-1400
__________________ SOUL PERFORMANCE PRODUCTS Quality Exhaust Solutions, Fair Pricing, and Outstanding Service
John Gaydos- Owner, Performance Specialist
Cell - (484) 883-6197 johng@soulpp.com
So just to double check, because you guys still have the 991.1 Base Without PSE still listed on your site, This new system will work with the 991.1 Base model Without PSE?
So just to double check, because you guys still have the 991.1 Base Without PSE still listed on your site, This new system will work with the 991.1 Base model Without PSE?
Not quite, and thanks for asking! The Base model Non-PSE has different side mufflers from the S Non PSE and PSE model cars. The muffler outlet pipes were routed to enter a single inlet tip rather than a PSE style dual inlet tip. What this means is that the Base Non-PSE side mufflers and their tips are not compatible with our valved exhaust (or any for that matter) that requires a dual entry tip and side mufflers with the outlet tubing offset to one of those tip entries to make room for the second exhaust pipe to enter the backside of the tips.
Our previous design included a Base Non-PSE to PSE style side muffler conversion kit and a set of dual entry exhaust tips to fit our system to that vehicle. However, we have not had a Base Non-PSE car in our facility to develop this conversion kit for our new exhaust system, and we are actively looking for a local car to make that happen. Our website is in the midst of being updated to reflect this on the Base Non-PSE product page. If you know of anyone local to the Philly area with an applicable car, please have them reach out
Not quite, and thanks for asking! The Base model Non-PSE has different side mufflers from the S Non PSE and PSE model cars. The muffler outlet pipes were routed to enter a single inlet tip rather than a PSE style dual inlet tip. What this means is that the Base Non-PSE side mufflers and their tips are not compatible with our valved exhaust (or any for that matter) that requires a dual entry tip and side mufflers with the outlet tubing offset to one of those tip entries to make room for the second exhaust pipe to enter the backside of the tips.
So you're saying that if I found a pair of side mufflers from a 991.1 w/ PSE, I could use those to replace mine and then use your system with new tips?
So you're saying that if I found a pair of side mufflers from a 991.1 w/ PSE, I could use those to replace mine and then use your system with new tips?
You are correct. For the valve controller to work you would need to wire it in and pull vacuum.
Oh man.. I LOVE my version 1 system - the only thing is the low end drone cruising on the freeway (usually when I close the valves anyway). Love the Soul system, it's been a huge change in attitude of the car. Thinking of long tube headers now.. how much louder would they be on my car with your existing system and what power gains would I expect to see?
Just got mine installed on Friday and drove it for about 50 miles. All I wanted to say is thank you for engineering such a fantastic exhaust system, both aesthetically and functionally. One very satisfied customer right here! Photos and videos coming soon!
Oh man.. I LOVE my version 1 system - the only thing is the low end drone cruising on the freeway (usually when I close the valves anyway). Love the Soul system, it's been a huge change in attitude of the car. Thinking of long tube headers now.. how much louder would they be on my car with your existing system and what power gains would I expect to see?
THanks!
The headers will definitely kick things up a noticeable amount in regards to sound level . Give me a ring at 484 883 6197 it would we much more efficient to explain it that way after having seat time between the two setups. As for power, we have expectations as to what they will make but will not make any claims until we receive reputable and repeatable third party dyno results (which we have arranged for early-mid May.
Originally Posted by SpeedZ
So are you guys going to have an exhaust ready for the 991.1 3.4 w/o PSE soon Seems like you managed to get your hands on some sample cars!
I expect we'll have something accomplished next month given the scheduling works out how we'd like
Originally Posted by slideways510
Just got mine installed on Friday and drove it for about 50 miles. All I wanted to say is thank you for engineering such a fantastic exhaust system, both aesthetically and functionally. One very satisfied customer right here! Photos and videos coming soon!
Thank you very much for chiming in with your feedback and the kind words. We are thrilled to be pushing the industry forward and a part of the community
The sound is exactly what I was looking for. Much more aggressive over factory PSE exhaust. Quiet with valved closed while cruising.
No droning whatsoever when cruising below 3400 RPM with valve closed.
Works perfectly with factory PSE option. Why wouldn’t it. ☺
High quality craftsmanship and perfect fitment.
Did I mention the sound is amazing?
Also, thanks Jon, Herb and the entire crew at TrackSpec Autosports in Fremont, CA for the install. They’re always professional, easy to work with, and super detailed oriented. Herb, even heat wrapped the silicon vacuum lines for extra protection for me!