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Yesterday we had a new Boxster GTS in house for sound symposer delete testing! The owner of the car, Jesse, is sensitive to in-cabin drone due to tinnitus from years of racing (our respect and condolences there) and offered his GTS up for testing. The whole process took us around an hour - even with the more complex Boxster top to deal with.
To start, here is a Porsche diagram to show the full scope and functionality of the sound symposer:
With all engine covers removed, here's the symposer as it sits from the factory:
Sound symposer pressure unit plugged with wing nut expansion plug:
Engine side of the cabin port plugged:
Interior side of the cabin port:
Engine bay with sound symposer hose deleted:
While the plugs we used will hold just fine, we're working on sourcing / producing OEM like caps that interface with the factory style clamps for a more complete result. The resulting delete is effective in reducing in cabin drone even on a stock 718. Jesse reports that the difference is quite noticeable and much to his delight. We'd like to continue testing on other vehicles and try to record decibels / video to show the full impact. If you're experiencing droning in-cabin the sound symposer delete might be a great idea to test to see if it's creating any undesirable notes in cabin. Here is a guide we made to show the process (on a Boxster GTS but the steps will be very similar for other models).
-Mike
Last edited by Soul Performance; 06-17-2021 at 06:58 AM.
@Soul Performance Mike, thanks for sharing all of this information, great resource for those of us interested in reducing the drone...
A quick question if I may, as shown by the arrows in the pictures below, are these ends of the tube hard plastic or is it a soft gasket that helps seal the connection? Thanks!
@Soul Performance Mike, thanks for sharing all of this information, great resource for those of us interested in reducing the drone...
A quick question if I may, as shown by the arrows in the pictures below, are these ends of the tube hard plastic or is it a soft gasket that helps seal the connection? Thanks!
You're most welcome! The tubes themselves are hard plastic. The expansion plugs we used to fill them are soft rubber on the inside and rated to a maximum of 100 PSI. We're working on a "snap in" solution.
-Mike
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Interesting...feel free to throw a set of those plugs in with my valved rear section (which should be close to its production slot) and I'll be happy to test these out on a GT4 and report the results
That will do it for sure! This means once you do that no need to plug the duct from the cabin side, behind the carpet right? Do you have the width of these expansion plugs? 1" or so? Thanks!
Wow, fantastic news, sign me up for those plugs. As discussed earlier with John, my ears are quite sensitive to in cabin resonance I hear when running stock pipes and valves opened with the controller. He mentioned the sound symposer was responsible for some of this, and they were working on a solution. Kudos to the crew at Soul for the solution and the DIY!
Before leaving for the day I wanted to chime in and say that having gone out with Jesse in the car (completely stock by the way), it was definitely a notable improvement. Less drone/resonance and what I'd call fake sound, that allows you to pick up on more quality and real engine and exhaust sound from outside the car. This is definitely an underrated mod to the driving experience, and is applicable for all exhaust configurations and we expect to make more of a difference on cars with exhaust modifications. Spread the word, play around with it yourselves, it works!
Best regards,
John Gaydos
Last edited by Soul Performance; 06-17-2021 at 06:55 AM.
Thank you John. Definitely on my list to do. Maybe these could be helpful as well from Amazon. Do we know what the inner diameter is for the vacuum line.
Thank you John. Definitely on my list to do. Maybe these could be helpful as well from Amazon. Do we know what the inner diameter is for the vacuum line.
Originally Posted by tdlondon
That will do it for sure! This means once you do that no need to plug the duct from the cabin side, behind the carpet right? Do you have the width of these expansion plugs? 1" or so? Thanks!
Originally Posted by Goodwood
Wow, fantastic news, sign me up for those plugs. As discussed earlier with John, my ears are quite sensitive to in cabin resonance I hear when running stock pipes and valves opened with the controller. He mentioned the sound symposer was responsible for some of this, and they were working on a solution. Kudos to the crew at Soul for the solution and the DIY!
Hey Guys,
The experimental expansion plug we used was a 1" version, so if you were to go out and order a pair for an inexpensive DIY job that is what worked for us. We won't be sending these particular plugs used in the experiment out to customers, as we are working on sourcing non-expansion plugs specifically designed for this type of plastic hose to form essentially a Sound Symposer Delete Kit. If successful the plugs should end up looking similar to the photo below.
Thanks, John. Hopefully the Symposer Delete Kit will be ready to ship by the time my Valved Exhaust is ready. Would like to do them both at the same shop appt.
Personally I think this needs a new thread. This (sound symposer) isn't exhaust anymore and I think everyone would benefit if this valuable information is separated into a new thread.
Personally I think this needs a new thread. This (sound symposer) isn't exhaust anymore and I think everyone would benefit if this valuable information is separated into a new thread.
Agreed. This sounds like a worth while understated mod. Deserves its own thread.
Personally I think this needs a new thread. This (sound symposer) isn't exhaust anymore and I think everyone would benefit if this valuable information is separated into a new thread.
Originally Posted by 808c2s
Agreed. This sounds like a worth while understated mod. Deserves its own thread.
I think you fellows may be right, I'll put some time into a separate thread later today or tomorrow to continue chatting about it there as well.
Alright guys, a Drone Reduction Sound Symposer Delete thread has been created. Those of you that have pursued this, please chime in with your feedback so they don't have to go dig through 70+ pages and 1000+ posts in this thread for this specific modification. Which by the way, take a moment to reflect on that. 70+ pages and 1000+ posts...that's pretty darn impressive for chatting exhausts with each other. Thanks for all your activity in here
06-10-2021, 09:04 PM
