inactiveuser7616

Hello...

Did you simply disconnect and leave hanging?

I'm guessing their vacuum actuated.....? If so I would think its best to cap them off.

Did you leave them disconnected?

It seems that even with the PSE button on they still are closed at lower RPM's as it seems to get really loud around 3500-4000 RPMs. Unless that's just the sound profile of the engine...? This is my first Porsche / flat 6 engine.

Any insight is appreciated. Thanks!

Mike in CA

They are vacuum actuated....you definitely need to plug the lines if you disconnect them. It's also a good idea to put caps on the valves themselves to keep out dust and moisture. Know that with the 991 GT3, unlike previous models, the valves are ECU controlled to optimize torque. I ended up returning them to a stock configuration after about a week.

meaker

Yes, you cap them. The sport exhaust is controlled by the ECU and does close from just above idle to 3700+/-rpms. I had mine disconnected with Sharkwerks but reconnected them with GMG. Don't really like the opening and closing but do like the less sound on the highway. Also I like the that my sport button is functioning.

Sloopy

I got the GMG and like the valves functional for same reason. Also got the GMG headers and have to say that the car is strong...

inactiveuser7616

Got it. I understand the back pressure benefitting low end TQ.

I've got the Fabspeed headers, sport cats, and side muffler bypasses with stock center muffler. However, I'd like some more grunt / volume at lower RPM's.

So before I purchase a center muffler bypass I'd like to hear/feel what the disconnected valves are like.

Thanks all.

calpolo17

I just screwed some small screws into the vaccuum lines to cap them.

Money2536 dynoed. No effect on power by disconnecting the valves.

inactiveuser7616

Gotcha. Thanks Calpolo!

MBDark

Sharkwerks midsection and I have mine plugged with some machine screws, and little rubber caps, then zip tied out of the way, been great for almost a year now.

Ducati1199

I've gone from SW center bypass, reinstalled OEM and removed side mufflers with fab speed bypass all in the quest of noise!!! I plugged and capped the vac lines from day 1. Slightly annoying that the PSE button is defunct now.
I'm sure you've seen the IPE full exhaust system that comes with RC that allows adjustment of valves? You can keep them open, closed or allow the ECU to open/close. I'm considering this option but there are a lot of IPE detractors on RL due to quality issues and a screwed up early dyno run that showed a large HP loss with the exhaust but believe that error has been corrected. Anyway another option/consideration and as always YMMV.

SamFromTX

The disconnected valves are great with sport headers and third muffler bypass. With your setup, bypassing the side mufflers as well, I think it will be unpleasantly loud and likely to drone, with or without vacuum plugging. Just something to consider.

inactiveuser7616

Thanks Sam. I think it's worth testing as I am looking for louder and whatever drone I have currently doesn't really bother me.

Granted...I have yet to take a long road trip on the highway. Sooooo.......

fxz

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much more reliable

SamFromTX

Definitely worth testing. Had my mechanic not talked me out of it 3 or 4 times, I would have done it. I may still try one day so if you do, please report back.