996.2 sound symposer install

Fitted a sound Symposer from a 991 to my 40thAE and very happy with the end results. Tried a number of different configurations & this setup works best, as it requires the high energy pulses from the intake just before the throttle body. This induction sound piped into the cabin is what is missing on the 996/7, if you have driven the 991 S in Sport mode you will know what is missing! The pulses are piped into the cabin (via the large rubber grommet in the far corner where the wiring loom shares) & out into the cabin via the triangle vent. Lots of panels needs to come off for the install but the end result is worth it. I didn�t want a loud exhaust as often it�s just too intrusive with unwanted drone! I used the intake boot from a 997, it has a flat round area to tap into, the Helmholtz Resonator needs to be connected to cancel out unwanted resonance otherwise it will interfere with the Symposers� designed working frequency & produce an unwanted & very unpleasant noise, trust me that is what my many experiments found! the Symposer & pipe is from a 991.1 with an extension pipe into the cabin, a vac solenoid to activate the valve or you can connect to Vac to have it always on. The pipe fittings are just what I had in my garage with sealant to prevent unmetered air leaks. you could just find the a shorter route for the sound to pass through into the cabin, but would mean making a hole in the fire wall. The additional induction sound starts at 3500 rpm & 50% throttle, it fills the cabin with just the right amount & increasing right up to red line, it�s not as loud as the 991 but it just takes it to the right level, if you ever driven a 981 GT4 or GTS, the induction noise from the Symposer in my opinion is too loud! 997 induction boot Use the flat round area to tape into. Wanted the ability to turn on/off Extend the outlet to the far corner & through into the cabin Not much space to work but can be done The outlet of the pipe is just the other side of the vent.

This is pretty cool! Thanks for sharing. Can you get some videos of what this sounds like?

This is awesome, can you share the part(s) number(s) required ?

Quotes source post: 19860380

When you say it needs to be connected what do you mean exactly? Right now I have mine plugged using the oil cap hack.

Quotes source post: 19861187

he means you ought to unplug it (return it back to stock).

These are the main parts: Symposer valve assembly 99111028003 997 intake boot 99711022300, will need additional tapping if you have an auto box or a 40thAE (vac booster pipe). connector to intake boot is a plastic water pipe adaptor with a locking nut Extension flexi pipe of the same type as the valve, unless you pipe it via the firewall Use this connector part if you want to go via the firewall 991 110 282 03 Vac solenoid & switch if you want to control it, simpler to have it aways on.

lol, I'm officially old. This is something that would probably be a deal breaker for me but if not, I would remove/disable it on any car I purchased on day one.

I fitted one of these to my 996 last year. It improved the induction noise but it was quit subtle. I recorded an acceleration run with the valve open and closed, and got an NVH colleague at work to analyse it, it was possible to see a difference objectively. Mine was fitted via the airbox as it was the easiest to do, albeit I knew it would not be optimal. Following this thread I decided to relocate it to the induction hose, albeit I've got a aftermarket silicone pipe, so not exactly the same as you. I also previously had the valve held open with a rubber band rather than vacuum, but I've now removed the diaphragm device completely and can move the valve by hand without it moving back to it's default position. I've just been back from my first drive with it and WOW what a difference! Valve open vs closed is now a night and day difference. The sound is much louder but not overpowering, and is best described as a smooth roar, very reminiscent of a 991 I got to drive a few years ago (funny that); I can see myself keeping the valve open all the time. Thanks for sharing this. If I can just get rid of my exhaust boom around 2.5krpm it'll sound perfect.

I have been around uncapped headers all my life on Race Cars and even Top Fuel Cars, the premise that loud= power is common, but after decades you tend to appreciate the Tone, Timbe, and Exotics sounds more than the sheer volume..... In 2011 when I drove the first 991 off the truck at the Porsche Dealership I was captured by the sound from it...Not loud but very pleasant in Tone, Timbe, with a bit of Exotic .... I too went on a mission to incorporate the sound into my 1999 3.4 996.....I loved the sound so much I invited others for a ride and did a dozen of the upgrades to local friends on 3.4's 3.6's and even some 997 3.8's ....I can say for sure the digger the displacement the better the sound....I haven't heard it on a 4.1 liter , they weren't even making 4.1 m96 at the time but I assume it would be the best...... I was urged to go comercial with it and make/sell a kit, but the install takes a good bit off fabrication skills that I felt were too involved for most Porsche owners and the support would be too much of a headache, so I never tried to commercial with any sort of a kit.....and of course there are those who thing it is somehow sacrilegious or "fake sound"... although it is really just a modified sound of the Intake and not a modified sound of the exhaust... To fully enjoy the Sound the exhaust needs to be at a lower/stockish volume.... So if you have done the "Orange Cap Mod" and like it, You have got a small taste of that this will do x4 .... Here is a Sound Clip from 2011 of my 3.4 liter 996 with stock exhaust mufflers...

Is this just for audio reasons? I'm not familiar with this particular hack.

The "sound symposer" reminds me of this video. This never gets old.... You Tube

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Yes, its just for acoustics /sound....all "high tech" cars spend tons of $$$ on the "acoustics" in the cabin.....Mann+ Hummell are the big Kahuna's in OEM intake systems.....They designed all the OEM Intake systems for Porsche Mercedes FoMoCo ect, and have the Patent on the "Sound Symposer" ....The amount of money they spend on R&D on Cabin Acoustics is staggering...and the engine sound is the main focus on sports cars or supercars ... Many places have regulations on the DB level / loudness a car can produce...

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Yeah people make fun of the "Fart Cans" used on Honda's also...lol...To me some sound good and some sound like ****... It all subjective and the OEMs try to guess what sound is preferred.....They actualy have rooms and panels of people listen to sounds and "vote" on what they prefer....lol Installing Helmholtz on the intakes of Sports Cars to me doesn't make sense ,I love the intake sounds especially on the newer GT3's...

Quotes source post: 19931480

"IF" you have a 991 Carrera it is there...You just have to look closely and know what you are looking for ...

Glad you found my post helpful, I did have an after market switchable exhaust on my car, which in Sport mode I found it a bit too loud outside of the car, sounded nice inside! Now the standard exhaust is back in the car, the Symposer adds whats missing! I was an Engine Induction System design engineer at one point which help a lot! Not for Porsche! Just make sure you check your install for air leaks every so often.