I can't confirm 100%, but I have a 991S without PSE, however I do have Sport Chrono on the car. When I press the SPORT or SPORT PLUS button the tone becomes increased by about 10% I would say. Its not significant, but its noticeable. Mostly, its my understanding that the SPORT / SPORT PLUS affect the throttle response more than exhaust, but I wouldn't bet the farm on my assumption.

On my car, I have a full Tubi Cat Back Exhaust after first trying the AWE Switchpath, that's how I got as far as I have into the exhaust plumbing as I did all the installs myself and learned the system. Here you can see the valves on both the Tubi and the stock exhaust, side by side.

 

That's interesting.
Since the Base Exhaust is quieter than PSE it would be harder to notice when the valves open.

Perhaps the thing to do is just install the PSE Center Section and then see if there is a difference in loudness (valves opening) with S/S+ mode engaged below 3K.
With PSE, the difference in tone from the valves opening is very noticeable, even at low RPM highway cruising.

 

99% sure that the "10% louder" tone you're hearing is the Sound Symposer opening up. That's the feature that's enabled in Sport/Sport +.

 

Not on my car, its a Cabriolet. Those sound tubes are in the coupes only.

 

Ahh, hadn't noticed, Doc. My bad!

 

Thank for the replies. It seems that some details remain unclear as to what the PSE button does. Yesterday I got under the car and looked at the valve actuator while my son switched from normal to Sport and and Sport Plus modes. Again this is with non-PSE system. The valves did not move at all (as I suspected).

So then next question is for those who have PSE and the Sport, Sport Plus modes if they can comment on what they notice while running through all combinations of options: normal with PSE on/off, Sport with PSE on/off, etc. Idle observations and low rpm would be appreciated. Not sure if with PSE center section (or an aftermarket one) one can see the valve actuator arms. Two days ago aI went to a local dealer to try one car with a PSE system just at idle. The sound change was very minor at idle. I do not think that the PSE button opens the valves at idle. Somehow I suspect that the PSE switch and programming does things to fueling and timing in order to get the associated tone, crackles and burps. I wouldn't be surprised even if the valve operation is different on acceleration vs. declaration with PSE programming. Thx in advance for those that can offer their observations.

 

As drcollie pointed out in post #9;
Base S exhaust has valves open at idle, therefore changing the mode, at idle, won't make any difference.
If you have dual exhaust tips you can feel the exhaust pulse.
Both pipes pulsing = valves open.
One pipe pulsing = valves closed.

While driving and below 3K is where I wonder if the valves respond to the S/S+ switch.
I assume if you can hear a change in loudness (with S/S+) then they are probably opening.
Just don't be fooled by the downshift and RPM jump, when you enter S/S+ mode.
You need to downshift first and then change modes to compare at same RPM (but below 3K).

With PSE and Switch:
The valves follow the switch, except above 3K, where the valves are open, no matter what switch position (or mode) you choose.
By default valves only open if S/S+ is selected or RPM exceeds 3K.
Switch lets you open valves in non-S/S+ mode.
It also lets you close the valves in S/S+ mode (which I usually do) so that they won't open until you reach 3K.

 

If the valves opened when engaging Sport or Sport Plus without PSE what would be the value of paying for PSE. Only to have a spare button with an exhaust logo on it?

I thought when I discussed with my tech at the dealer the non PSE cars only open the valves once at the mid 3000rpm range. Cold start you might get some rumble but once idle settles not the case.

 

I would think the main advantage of PSE is the new center section with X Pipe, which is louder, when the valves open, and must be part of what gives the noises everyone seems to like so much.

Just tell us more about your Kline

 

[/PHP][/PHP] I m not questioning the value of PSE. I'm commenting on the non PSE operation. I love the Kline. It's a beast when you want it to be and mellow when not engaged. Very happy with it and the quality of the build.

 

Just to clear something up.

If you leave the valves closed, either by not activating Sport/Sport+ or by not clicking the exhaust valve button, the valves can actually remain closed all the way to redline, providing you are light on the throttle input.

There are two conditions that need to be satisfied for the valves to automatically open without any options: (1), over ~3,300rpm, and (2) about 30% or more throttle input.

So, if you're light on the throttle, you can keep the valves closed as long as you want. I wish this weren't the case, as I occasionally enjoy hearing the car rev up to high rpms without the exhaust overpowering the engine/induction noise.

 

That's good info Christophosphorus.
I would never have known as I think it's rare for PDK to exceede 3300 RPM w/o applying over 30% throttle.

 

so I had a 2009 C4S with PSE. I was under the impression that when activating PSE the valves on the secondary muffler on either side closed therefore bypassing the muffler.

Later I added an xpipe that bypassed the center muffler, the sound was great. I agree that at idle there was a significant change in sound when PSE was switched from On to Off or vice versa.

is this understanding incorrect? Does the 991 also have a center and two secondary mufflers or is the setup different now?


thanks.

 

You've got it right. 991's are configured with a center and two sides.

 

So can someone confirm my summary below.

Non-PSE valves open over 3000 rpm in sport mode. Slightly louder AND no pops and crackles.

PSE. Valves open all the time AND is louder due to different centre muffler AND has pops and crackles.

Question is...is PSE worth it just for some burps and slightly extra noise?