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I considered several ways to control the valve automatically. If you want rpm based operation of the valve, your idea sounds entirely viable.
I came to the conclusion that I don’t want it rpm based though.
I realised that when I’m trying to be discreet or stealthy (quiet) I still want to use the full rev range. I don’t want to be forced by neighbourly consideration to labour the engine at low revs and screw up my bearings.
Also, the only time I bury the throttle is when I’m on open roads away from schools, pedestrians, police and neighbours, and this is when flow needn’t be restricted or sound muffled.

Conclusion, it needs to open according to throttle position, progressively. Then it will be intuitive because we already know the throttle is the loud pedal.

It’s easy to do by wiring the throttles potentiometer to the valves 12v connections. You might need a capacitor or rectifier in between or something but I’ll get an auto electrician in to do it.
I will have the cat bypass valve and QS valve both operate in parallel so the progression is from quietest possible to loudest possible depending on throttle pedal position.
The electronic control gear that comes with the QS and the valve I get for the cat bypass will co exist with my hard wiring as we will also have a switch on that hardwiring to disconnect the pedal from the exhaust in case I want to lock the exhaust in any particular mode for any reason ie. full open for a track day or fully silenced and catalysed for tests, economy mode.
 

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Discussion Starter #62 (Edited)
I considered several ways to control the valve automatically. If you want rpm based operation of the valve, your idea sounds entirely viable.
I came to the conclusion that I don’t want it rpm based though.
I realised that when I’m trying to be discreet or stealthy (quiet) I still want to use the full rev range. I don’t want to be forced by neighbourly consideration to labour the engine at low revs and screw up my bearings.
Also, the only time I bury the throttle is when I’m on open roads away from schools, pedestrians, police and neighbours, and this is when flow needn’t be restricted or sound muffled.

Conclusion, it needs to open according to throttle position, progressively. Then it will be intuitive because we already know the throttle is the loud pedal.

It’s easy to do by wiring the throttles potentiometer to the valves 12v connections. You might need a capacitor or rectifier in between or something but I’ll get an auto electrician in to do it.
I will have the cat bypass valve and QS valve both operate in parallel so the progression is from quietest possible to loudest possible depending on throttle pedal position.
The electronic control gear that comes with the QS and the valve I get for the cat bypass will co exist with my hard wiring as we will also have a switch on that hardwiring to disconnect the pedal from the exhaust in case I want to lock the exhaust in any particular mode for any reason ie. full open for a track day or fully silenced and catalysed for tests, economy mode.
Wow. Please keep us updated on your progress and share whatever you are comfortable sharing (especially coupling valve position to throttle position).

On a side note, it looks like the Torque Pro app can read RPM and throttle position via OBD2 and acceleration via the phones internal sensors (see attached photo). All the info you need seems to be available via simple Bluetooth connections. It looks like you could use any or all of those readings along with IFTTT to trigger valve position via the Sound Architect app. Plus, it would be easier to have multiple settings depending on preference and occasion. It's certainly worth looking into.
 

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I agree. The possibilities doing it all on apps are endless but will take knowhow I don’t have and can’t readily access to implement them. The hardwire solution will be only a temporary one to get me going until someone figures out the app route hopefully.
I need to see if a 3” diameter cat will fit chopped into the link pipe and leave room for a bypass pipe by it’s side. The plumbing is the immediate challenge. I can definitely be done but it needs to be done well.
 

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I agree. The possibilities doing it all on apps are endless but will take knowhow I don’t have and can’t readily access to implement them. The hardwire solution will be only a temporary one to get me going until someone figures out the app route hopefully.
I need to see if a 3” diameter cat will fit chopped into the link pipe and leave room for a bypass pipe by it’s side. The plumbing is the immediate challenge. I can definitely be done but it needs to be done well.
We are still waiting for the video Floro bro. I'm thinking of getting it. Is it worth it? I have the race exhaust. I want less raspy noise and the possibility to lower the noise in the morning (race exhaust is loud).
 

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Sorry dude I forgot. Just short clips of throttle blips while waiting for the Mrs to get the essentials in the shop but if you listen on the factory 4C stereo via BT you will hear what I heard and I’d say it gives some idea.
To my ears, closed (straight through pipe) sounds louder in the mid range and more of a growl. Open sounds quieter in the mid range but louder and deeper in the low frequency range. The subsonic frequencies seem to be louder though. The car vibrated on startup when parked close to a wall behind, its ear splitting at idle! That said, the mid/low frequency drone at 65 plus is gone with valve open.



CLOSED

OPEN
 

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Sorry dude I forgot. Just short clips of throttle blips while waiting for the Mrs to get the essentials in the shop but if you listen on the factory 4C stereo via BT you will hear what I heard and I’d say it gives some idea.
To my ears, closed (straight through pipe) sounds louder in the mid range and more of a growl. Open sounds quieter in the mid range but louder and deeper in the low frequency range. The subsonic frequencies seem to be louder though. The car vibrated on startup when parked close to a wall behind, its ear splitting at idle! That said, the mid/low frequency drone at 65 plus is gone with valve open.



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Thanks Floro.
 

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Discussion Starter #67
Sorry dude I forgot. Just short clips of throttle blips while waiting for the Mrs to get the essentials in the shop but if you listen on the factory 4C stereo via BT you will hear what I heard and I’d say it gives some idea.
To my ears, closed (straight through pipe) sounds louder in the mid range and more of a growl. Open sounds quieter in the mid range but louder and deeper in the low frequency range. The subsonic frequencies seem to be louder though. The car vibrated on startup when parked close to a wall behind, its ear splitting at idle! That said, the mid/low frequency drone at 65 plus is gone with valve open.



CLOSED

OPEN
Thank you for posting the videos! What exhaust did you have before? Are you glad you got the valved exhaust? What mode do you typically drive in? Does it have the pops when you lift off the accelerator when the valve is closed?

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No problem. I had the factory sports exhaust. I changed mainly to get rid of the cruising drone by having the valve open. I would say even in closed it sounds better and the pops are quieter I think. I really noticed a fart like sound before, not so much. I drive it closed as i like the rasp of the mid frequencies. If I'm cruising at drone speeds, I switch it.
 

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I recently swapped the factory race exhaust into the car and removed a Novitec Stradale valved exhaust that I will clean up and post for sale here shortly. It is good for people who want to keep quiet around the neighborhood or track but also to have the option of a louder exhaust with the click of a remote.
 

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No problem. I had the factory sports exhaust. I changed mainly to get rid of the cruising drone by having the valve open. I would say even in closed it sounds better and the pops are quieter I think. I really noticed a fart like sound before, not so much. I drive it closed as i like the rasp of the mid frequencies. If I'm cruising at drone speeds, I switch it.
Floro, I want to make sure I understand. The Quicksilver exhaust is louder than the race one when the valve is closed? I want to get it because I want to make my car more quiet. Also, do you think it was worth 1500 bux?
 

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Discussion Starter #71 (Edited)
No problem. I had the factory sports exhaust. I changed mainly to get rid of the cruising drone by having the valve open. I would say even in closed it sounds better and the pops are quieter I think. I really noticed a fart like sound before, not so much. I drive it closed as i like the rasp of the mid frequencies. If I'm cruising at drone speeds, I switch it.
Interesting. So from what your saying, having it automatically change from open at low RPM to closed at higher RPM (above when it drones) may not be necessary since you tend to drive with it closed most of the time.

I also find it really interesting that the low freq are louder when the valve is open and the mid freq are louder when it's closed. Are the higher freq also louder with it closed? From what I've read the Centerline Stradale has a lot of low freq bass due to its resonator. Maybe this exhaust has a similar effect, though maybe not as dramatic.

The more I think about it, the more I think I'd like to have it automatically switch from drone free low RPM loud to raspy mid/high RPM loud... all the while keeping a bit of the crackling but not so much of the farting. That sounds darn near perfect.

I found a device that may help with auto switching modes...


I wonder if that will work with this exhaust...

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Interesting. So from what your saying, having it automatically change from open at low RPM to closed at higher RPM (above when it drones) may not be necessary since you tend to drive with it closed most of the time.

I also find it really interesting that the low freq are louder when the valve is open and the mid freq are louder when it's closed. Are the higher freq also louder with it closed? From what I've read the Centerline Stradale has a lot of low freq bass due to its resonator. Maybe this exhaust has a similar effect, though maybe not as dramatic.

The more I think about it, the more I think I'd like to have it automatically switch from drone free low RPM loud to raspy mid/high RPM loud... all the while keeping a bit of the crackling but not so much of the farting. That sounds darn near perfect.

I found a device that may help with auto switching modes...


I wonder if that will work with this exhaust...

Sent from my Pixel 2 XL using Tapatalk
No, I would still prefer to have it change according to throttle position (free flowing on throttle threshold) and vehicle speed (anti drone mode at 60 plus ). I keep it in one mode most of the time because changing mode is a hassle, not because I like it that way. This is why I want the automation.

When the valve is open, the gasses go into the resonator. Resonators make low frequencies. They reduce midrange and high frequencies.
 

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I emailed Alfa works, and they said basically it takes out the drone on highway speed.
"the quieter mode is really more about the horrendous drone you get at motorway speeds, this is eliminated and the exhaust is a little quieter with no pops or bangs"

I want to get a valved exhaust to replace my oem sport exhaust as well. Driving to track (2 hours drive) gets so annoying. I had to crank up the radio or yell at the phone when people call me.
 

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I drove it valve open today for 60 odd miles. I think the resonator causes a drop in the power you notice while accelerating. The power seems to drop off from 90 mph. Below that it seemed to pull as hard as with the valve closed.

Tried N and D and still felt like the quiet mode robbed it of a few hp.

Only one drive so I’ll see if I think the same tomorrow.
 

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Its true, the shut valve does kill the drone too. It‘s drone free in both modes, loud (valve closed) and quieter (valve open).
 

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Discussion Starter #77
OP updated with the latest info.

Sent from my Pixel 2 XL using Tapatalk
 
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