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Discussion Starter · #1 ·
Hello guys I hope you are all well and safe.

I have a 2017 CTSV and wanted to know when the valves are in Tour mode, does it fully close when idle? Or just around 80%
Mine when closed I can see the air coming from both tips ( the one with the vlave closed and the other one) so it doesnt fully close.
So wanted to see if its normal.
My understanding of NPP is when you close the valve, the air from the engine goes the other path in the muffler which is more restrictive which leads to a quiter sound.

Thank you
 

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2009 Sedan
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"Flaps are always open at idle (cold or warm). I'm not sure of the exact rpms or throttle % but if you slowly take off you should be able to hear it close somewhere around 2-3k rpms. When you get on it they will open up. I have the NPP with cat delete pipes and I hear it so i'm sure you should be able to as-well."

Found this on a Camaro forum.
 

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"Flaps are always open at idle (cold or warm). I'm not sure of the exact rpms or throttle % but if you slowly take off you should be able to hear it close somewhere around 2-3k rpms. When you get on it they will open up. I have the NPP with cat delete pipes and I hear it so i'm sure you should be able to as-well."

Found this on a Camaro forum.
I'm not sure this is accurate for our cars. NPP exhaust on the corvettes and camaros opens when you get on it (when the ECU demands it per throttle), but our cars dont have NPP, they have exhaust that is set by the driving mode. I do believe the valves open on a start but if you are in Tour mode, they dont appear to open when you punch it. I could be wrong.
 

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I'm not sure this is accurate for our cars. NPP exhaust on the corvettes and camaros opens when you get on it (when the ECU demands it per throttle), but our cars dont have NPP, they have exhaust that is set by the driving mode. I do believe the valves open on a start but if you are in Tour mode, they dont appear to open when you punch it. I could be wrong.
Gotcha. I went searching for NPP. If they don't actually have NPP, then that wouldn't apply I imagine.
 

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Discussion Starter · #5 ·
Its the same as the Camaro and Corvette the NPP is the name of the system, same valves, same mounts and even the same electric actuators with the same plugs. I even tuned the valves by using hptuner to be fully closed on Tour mode and fully open on Sport and Track.
Can you guys check if theres any air coming from the tip that has the valve when in Tour?
Thank you
 
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