JC997

My first thought and from what I have read the PSE does not add more torque or horsepower. However, today when I was driving my car onto the highway, I was at about 5k rpms and it was very loud so I turned off the PSE. Right when I turned it off, I experienced notable decrease in power and speed which struck me as odd. I thought maybe this was my imagination, so I tried it later in the day and the same thing happened.

The car does have a few enhancements such as Soul headers and cats along with a Softronic tune. It does get pretty loud at times and that was the reason I turned the PSE off today. Could it be that turning off the PSE restricts the exhaust flow reducing power?

jamesinger

Is your button the exhaust button or the sport button?
When I turn off sport while driving with my foot on the gas, it feels weird, almost like it hates that...the lag is obvious, so I try to turn it off with my foot off the gas or when I stop.
Porsche claims the PSE is just for noise but the existence of a flap does restrict some flow. IDK how noticeable but it has to do something right?

BondJ

PSE adds nothing except noise.

Petza914

A little of both, but not sure it's a perceptible amount It shifts the torque curve lower when the valves are closed by increasing back pressure and at higher RPMs opens them to increase flow, which helps with HP. That's why the system automatically closes the valves at low rpm even when it's in sport mode.

wjk_glynn

Folks should clarify whether they’re talking about .1 vs .2 cars, as PSE behaves differently between those very different powertains.

On the 997.2, PSE doesn’t add power. And the 997.2 valves don’t automatically open/close at different RPMs like the 997.1

The 997.2 PSE valve position is solely per the dash button position.

I’m not as familiar with the .1, but Pete (Petza) has provided many detailed descriptions of how it works over the years.

BondJ

Honestly, across all models, it’s just noise. A good quality straight-through cat back exhaust, with no other mods, will produce very small hp gains. The PSE consists of just a bypass valve and actuated flap. It produces no measurable power increase. Crucially, Porsche does not claim any power increase. You can bet your last buck it would if it could!

Busta Rib

This is a key question and distinction. Turning PSE on/off using the exhaust button is for noise only. If you turn PSE on by pressing the Sport button, a lot of other variables are changed: PSE, increased tolerance on driving nannies, and sharpened throttle response. If you install aftermarket software like GIAC, Fabspeed, Softronic, the throttle response is even more noticeable. That is likely what the OP is experiencing. Not necessarily more power, but more sensitive throttle.

groovzilla

PSE is the best sound. Should be stock on all 997's. Why they made a button to turn it off I'll never know.
If you don't have PSE and want the closest almost identical sound, I suggest Fister Muffler system which is on my current 997 C4.
I've had PSE in my 996's and 997's and also Gundo Hack and the FVD Brombacher Level 2 exhaust kit.
Those are close but no cigar.
IMO Fister's are for sure almost identical to PSE in every way.

JC997

Apologies for the delay in responding. The car is a 997.1 and it has the sport button. It must be the throttle response from the tune that feels like a decrease in power.

jamesinger

^^^ that is the key right there. Sport button has a lot of other variables over just opening exhaust flaps. Also, if you want permanent PSE open sound, you can easily mod your PSE to be permanently open. I have the Fisters, which sounds identical to my ear, and I never wince when I start my car, even when it is 6am or so. All other cars I have owned with exhaust, I feel bad for starting the car early in the morning or really late at night. I do not feel this way one bit with my Fisters.

Softronic

Hello,
Yes you are 100% correct as Porsche does not show any gains for their exhaust.


Best,
Scott

///Malcontent

I've been playing with PSE on my Carrera GTS (997.2, of course) while adapting the actuation system to an Akrapovic "Race" full exhaust system.

I'm not sure if there is a load component to the 997.2 ECU's control of the PSE, but it seems like the valves are closed at high RPM under no load. I made a video with some captions saying what was going on.

Actuator in: Vacuum applied, valves closed, "quiet mode" engaged
Actuator out: Vacuum removed, valves open, "loud mode" engaged

wjk_glynn

That is super helpful, thanks so much.

Does this timeline look correct?

1) 0m00s - Engine is off, valves are open
…
Edit: Removed the rest of the time stamps as they’re no longer valid after the video was updated.

Thanks.

Karl.

///Malcontent

I edited the video to add captions of what was going on. See the updated video link above.

I didn't take the video with the intent of documenting PSE control and actuation. I was just verifying that the actuators moved as expected when the PSE was pushed. I was quite surprised to see that there's another control, likely the ECU, being applied.

swoardrider

i assume you’ve done extensive dyno time to see this on stock cars across all platforms

I have the aftermarket remote control to override the PSE’s exhaust valves that the ECU from controls on my GTS. I use it to keep the car quiet at tracks like Laguna Seca. when my GTS was all stock I never noticed a difference between The exhaust valves open or closed.
as soon as I went with an X pipe, headers, race cat, and 100 octane file, my butt dyno and throttle position seems to feel a difference in power between the exhaust valves always open vs always closed on the racetrack…or maybe I’m just high on the extra exhaust fumes