Originally Posted by BWJ

I have a 718 Spyder and recently installed Soul's street valved exhaust with the overaxle pipes. I am still running the OE valve control. The sound of the exhaust is a big improvement over the stock set-up and the installation was very straight forward due to the very precise fitment of the parts. Parts quality is first rate. The one drawback was noticeable drone between 2000-2500 RPM. Above and below that, no drone, just better sound quality than OE. Once the valve controller opens things up (app. 3800 RPM), the system just rips in a very melodious way. However, having read about the potential contribution of the intake sound mechanism to the drone issue, I decided to see what disconnecting it would do. Rather than tear out the entire mechanism and have to plug the subsequent holes, I decided to simply plug up the sound tube where it enters the passenger compartment. All you have to do is disconnect the sound tube where it meets the right angle plastic tube fitting that attaches to the firewall, then stuff that right angle fitting with rolled up, high density, closed cell foam. I used a piece of 1/2 inch foam rolled into a tube shape and then stuffed inside the plastic tube. Just make sure it goes in deep enough to allow the sound tube hose to reconnect to the plastic tube when you are done. When finished, everything looks OE. To be sure I eliminated any contribution the sound tube was making to the drone issue, I also plugged the vacuum hose that operates the sound tube's flapper valve next to the intake box. This is a small curved rubber hose that connects the vacuum line to the flapper valve and is easy to access since it is not buried under other engine parts. The rubber hose is asymmetrical in that one end has a smaller inside diameter than the other. The small inside diameter end goes to the flapper valve and the larger inside diameter end of the hose goes to the vacuum line. If you get a 1/4" diameter allen head threaded plug (1/2 inch long or less), you can thread it into the large diameter end of the hose (barely touches) until it gets to the middle of the hose where it will dig in tight to the smaller diameter portion of the hose, creating a tight fit with no chance of vacuum leakage. Using this larger size threaded plug instead of a smaller diameter one not only provides a leak proof fit but also insures that there is no way the plug could ever be sucked back into the vacuum system, since it is much larger than the inside diameter of the vacuum line. Make sure you thread the fitting in far enough to leave the full length of the larger end of the hose available to properly fit over the vacuum line which has two raised edges (ridges) that should be covered by the hose when pressed on. Again, final result looks totally OE and since the operation of the flapper valve is vacuum controlled and not monitored by the ECU, no CEL possible. Now for the really good news: Virtually no drone at any RPM! A tiny bit is still audible between 2-2500 RPM but you really have to listen for it now as opposed to being annoyed by it in the past. For me, the results were almost unbelievable, the difference was that great. I understand that Soul designed this exhaust system to have the least drone with the valve control open all the time and that is the way they recommend it be used, but if you want to keep your valve control OE, or want to eliminate as much drone as possible under any circumstances (I'm sure it would work with the valves open, too), I can highly recommend this approach.

Originally Posted by Westcoast

@iliveoncaffiene Do you think something stuffed into the sound symposer would be enough? Can this be done from inside the cabin?

Originally Posted by iliveoncaffiene

No. This is what I had done at first and it was barely noticeable of a difference.
It's also not accessible without taking off the seatbelt plastic, the metal bar (4xT30 screws), and the trim piece under that. All of that just to pull back the carpet behind the seats a little (this is in the GT4 - idk the process in the Spyder).

The engine cover itself is 12 more T30 screws.

Originally Posted by MEM82

Hi always, I will find out today. I haven't done WOT yet myself...but nice moderate throttle...but the shop owner took it for a ride and tested everything and he couldn't trigger it either and I made sure he pushed it a bit.

Originally Posted by BWJ

I have a 718 Spyder and recently installed Soul's street valved exhaust with the overaxle pipes. I am still running the OE valve control. The sound of the exhaust is a big improvement over the stock set-up and the installation was very straight forward due to the very precise fitment of the parts. Parts quality is first rate. The one drawback was noticeable drone between 2000-2500 RPM. Above and below that, no drone, just better sound quality than OE. Once the valve controller opens things up (app. 3800 RPM), the system just rips in a very melodious way. However, having read about the potential contribution of the intake sound mechanism to the drone issue, I decided to see what disconnecting it would do. Rather than tear out the entire mechanism and have to plug the subsequent holes, I decided to simply plug up the sound tube where it enters the passenger compartment. All you have to do is disconnect the sound tube where it meets the right angle plastic tube fitting that attaches to the firewall, then stuff that right angle fitting with rolled up, high density, closed cell foam. I used a piece of 1/2 inch foam rolled into a tube shape and then stuffed inside the plastic tube. Just make sure it goes in deep enough to allow the sound tube hose to reconnect to the plastic tube when you are done. When finished, everything looks OE. To be sure I eliminated any contribution the sound tube was making to the drone issue, I also plugged the vacuum hose that operates the sound tube's flapper valve next to the intake box. This is a small curved rubber hose that connects the vacuum line to the flapper valve and is easy to access since it is not buried under other engine parts. The rubber hose is asymmetrical in that one end has a smaller inside diameter than the other. The small inside diameter end goes to the flapper valve and the larger inside diameter end of the hose goes to the vacuum line. If you get a 1/4" diameter allen head threaded plug (1/2 inch long or less), you can thread it into the large diameter end of the hose (barely touches) until it gets to the middle of the hose where it will dig in tight to the smaller diameter portion of the hose, creating a tight fit with no chance of vacuum leakage. Using this larger size threaded plug instead of a smaller diameter one not only provides a leak proof fit but also insures that there is no way the plug could ever be sucked back into the vacuum system, since it is much larger than the inside diameter of the vacuum line. Make sure you thread the fitting in far enough to leave the full length of the larger end of the hose available to properly fit over the vacuum line which has two raised edges (ridges) that should be covered by the hose when pressed on. Again, final result looks totally OE and since the operation of the flapper valve is vacuum controlled and not monitored by the ECU, no CEL possible. Now for the really good news: Virtually no drone at any RPM! A tiny bit is still audible between 2-2500 RPM but you really have to listen for it now as opposed to being annoyed by it in the past. For me, the results were almost unbelievable, the difference was that great. I understand that Soul designed this exhaust system to have the least drone with the valve control open all the time and that is the way they recommend it be used, but if you want to keep your valve control OE, or want to eliminate as much drone as possible under any circumstances (I'm sure it would work with the valves open, too), I can highly recommend this approach.

Originally Posted by Soul Performance

"This guy just put a sock in it"

Pete I just sprayed water all over my desk laughing at that

For those chiming in on this topic, we feel this is a SERIOUSLY underrated mod and a real gamechanger. Professionally documenting this with photos and video, along with putting together a little kit for those that want to do it, is a priority for us and we aim to have this done very soon for those that want to try it. Any photos or explanations of those that have tried this successfully, please post in this thread so we can all reference it moving forwards

Regards,
John Gaydos

Originally Posted by Big Belly 711

The first and one of the only mods I plan on having done in the CGTS (once it's here!) are the Soul over axle pipes ....I'm not the handiest guy so will have a shop do the work....can anyone out there estimate the time it takes to complete this mod (estimated hours of labor)....I know it varies and there are some variables, but just a ballpark? They are an Armytrix shop so they haven't installed the Soul's yet and the cost will be based on the time it takes.....thanks for input!
Would also be helpful to get an estimate on the time it takes to install the Soul Valve Controller (The CGTS will be PDK)...

Originally Posted by Skydude

Were you able to find out and has your check engine light come on?
I did the same and the CEL came on about 300 miles later. Got mini cat spacers from Amazon.

Originally Posted by Big Belly 711

The first and one of the only mods I plan on having done in the CGTS (once it's here!) are the Soul over axle pipes ....I'm not the handiest guy so will have a shop do the work....can anyone out there estimate the time it takes to complete this mod (estimated hours of labor)....I know it varies and there are some variables, but just a ballpark? They are an Armytrix shop so they haven't installed the Soul's yet and the cost will be based on the time it takes.....thanks for input!
Would also be helpful to get an estimate on the time it takes to install the Soul Valve Controller (The CGTS will be PDK)...

Originally Posted by Westcoast

Given that plugging the symposer doesn't provide the desired solution I guess that I may be going to have to open the engine compartment again...

Looking forward to hearing back on this:

Originally Posted by iliveoncaffiene

Update: I have to alter my "reduced by 80%" statement from above. It probably reduced it ~30-40% overall, and it tightened the rev range it appears in. Before, anywhere from 2000-2800 was a no-go. Now it's ~2100-2400rpm, and is slightly more bearable.
So, it isn't the "oh my god" change I thought it would be.

Interesting note: it only happens when in gear. I can rev the car (while rolling and standing still) in neutral and hold it at 2200rpm (prime drone range) and there is absolutely 0 drone. But as soon as I'm in gear it's there again. This may be something I'm overlooking but does anyone know why this would be?

Originally Posted by lovetoturn

So now with the sound symposer disabled, the drone range and level reduced, maybe a Helmholtz resonator set at 2200 rpm could almost wipe out the rest of the dreaded drone. Wouldn't that be nice.