rjn1

I removed it 9 months ago with no subsequent faults. I have an aftermarket straight through exhaust and 200 cell cats, so cabin noise is always loud. However the timbre of the sound is more exhaust based rather than intake. It's not a huge difference. Removing the symposer pipe makes no difference to exhaust Rice Krispies sound.

speed21

Thanks. I understand that a straight through system is going to bring a lot of additional cabin noise, some good and some bad, so that would mean an increase in interior drone over stock levels. Did the removal decrease that particular drone element?

Carcam

I disconnected it but instead of removing it, I left the bulkhead part attached and duct/electrical taped over each end. It seems solid enough to not rattle off and this way both ends are sealed.

This difference is noticeable but not as significant as is the 991 C2S. Also, in the 991 C2, we removed the rear carpet panel under the back window and plugged the actual port where the symposer sound came in. I removed the panel on the turbo and the insulation but couldn't see where the sound port came in. I guess if the hose is disconnected and blocked, that should be enough.

rnj, thanks again for the tips and pictures!

TerryO

Thank you, all, for sharing your experiences and opinions on deactivating the Sound Symposer "drone" in 991TTs. They were most helpful.

Last week I had my Symposer "deactivated" by the lead tech at one of the local Porsche Service Centers. The tech did some research over the previous week, and then did three things when I brought the car in: 1) toggled off the "Symposer present" bit in the OBC; 2) shut-off the vacuum line feed to the Symposer sound-valve; and plugged both ends (cabin & engine) of the Symposer sound tube, and then reconnected.

Just toggling off the "Symposer present" bit was a simple and effective solution (he just had to find the "bit" <smile>). He said he did the vacuum line feed shut-off to help insure that there were no side-effects to the engine management system (my memory is unclear on exactly how the tech did this). And he plugged the sound tube, internally, at both ends because he did not want have the Symposer tube passively resonating the "droning frequency" into the cabin. Clever, thoughtful guy.

The drone is gone - period!
No more noise-fatigue while cruising at 73mph on the freeway. I can hear more engine noise and exhaust noise without the drone, as well as induction noise coming from "outside"; and I can hear the pops and crackle on throttle lift more clearly. But now the car is crying-out for a real sportier exhaust sound!

The whole procedure took less than half-hour. No codes were thrown (the tech "guaranteed" none will be coming). And the tech said the would not invalidate the warranty. He said he can reverse all three modifications in less than 15 minutes if desired anytime in the future.

Deactivating the Sound Symposer and removing the resonating drone during throttle application, has significantly enhanced my enjoyment of the 991TT.

(BTW - while the car was in the shop, I swapped our the PZero tires for Michelin PSS. As I described in another post, this was a HUGE improvement in both handling, noise and ride.)

Terry

991TurboS

My symposer broke!

PMNewton

I took mine apart and removed the butterfly valve but left everything else intact. The actuator will still rotate and the computer still recognizes that it is present but with the actual butterfly valve obstruction removed the effect is that it is always "on."

My only issue with the symposer was the abrupt way in which it engaged during throttle opening. I like the sound but didn't like the delay in activation and on-off characteristic of the vacuum actuator. When I pressed the accelerator there was a brief delay and then a sudden boominess of the symposer opening. It didn't seem very analog. I haven't driven it yet but if it is too loud I'm going to experiment with stuffing different densities of foam into the pipe to reduce the overall volume but leave it always open. I'll report back when I have a solution...

- Patrick

FBA

I had the vacuum line capped and removed. Then we taped the vacuum line input shut. There's a bit less drone (Fabspeed exhaust/ headers), but there's far less sound variance through throttle positions. That was so annoying.

I think that's as good as it'll get.

Blocking the pipe should not have any effect AFAIK.

Would be nice if we had active noise cancellation, like the Jeep SRT's

991TurboS

The symposer is a direct route into the cabin. Mine is still hooked up and works after being replaced by the dealer, but I used it as a route for my two AL Priority Diodes on my rear laser shifter setup. The ribbed part of the hose takes a dremel hole very well as the exit point for the cables. When all finished, I sealed it back up up with black silicone.

Tom M'Guinn

Has anyone done this on a 991.2 Turbo and/or able to confirm its the same as the parts shown here? Also, if TerryO is still around, can you share the name of the dealer/tech who disabled your symposer in the Bay Area?

928 GT R

Bump, good information... Is it confirmed that there is only one "symposer tube"?

aft86

Yes, there is only one tube going into the cabin on the driver's side.

Also, I feel like we shouldn't be taping anything on these cars. Working on a plug to click in there.





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928 GT R

Very nice, Thank You!

abiazis

Why did they do the symposer to begin with?

onfireTTS

hcvone

Plugged mine when the headers and exhaust went on, now all I hear is Kline.