IRM

Very interesting. I have Cargraphic's valve controller - So if we keep the exhaust button off and valve controller forces the valves always open, do we have the best of both? i.e. Symposer is disabled and exhaust valves are open right? does the exhaust button on add anything on top re. exhaust sound? Thanks

hugo993

good job !! congratulation soul !

Soul Performance

Regardless of GeaTeaTea’s testing above, deleting the symposer from the car reduced drone in the car in all conditions we experienced. We were specifically looking to reduce resonance/drone valves closed at cruising speeds under light or moderate throttle, where you want to be most comfortable in cabin, and it had the intended results.

Merlotsj

You may be onto something IRM. I have Soul’s valve controller, and I use that rather than the console exhaust button to open my valves. I did not notice much difference when I did the DIY method several days after it was first posted in the Soul exhaust thread a couple of weeks ago. Also worth noting - I previously had the valve controller connected to a switched power source, so it came up in “valves open” mode every time I started the car. I recently changed to an always on power source for the valve controller, so it stays in the mode it was in when I turned the car off when I next start the car, so I was always in valves open mode with the valve controller unless I specifically set “valves factory - set by console switch” because I wanted stealth mode. I switched the power source for the valve controller a few days after modifying the symposer tube.

needmoregarage

^GeaTeaTrea: thanks for that info! Where did you place the recording device during your tests?

josephr25

I wonder how this would sound with a race pipe now

clutchplate

Of all the recordings I've heard of this engine I prefer the sound from the cabin interior so that's probably coming from the symposer and not the exhaust. I wouldn't bypass mine as I consider drone a non issue but might be interested in a symposer that's tuned a little sweeter.

iliveoncaffiene

I unplugged the vacuum line to the symposer with Soul's Resonated Race Exhaust - it went from nearly unbearable drone and booming in the 2000-2800rpm range to a pretty livable loudness in the 2200-2600rpm range.
Probably close to 50% reduction just unplugging the line.

dnimi123

I have the CG valve controller. I ll test this and see. Thx. I still wouldnt mind going back in to the engine bay at some point and unplugging the thing as well...

sehyang82

Take my money! I was getting tired of this drone at 2200~2800rpm especially with the top up, and this rpm range is where your gears put you at the cruising speed mostly. Kline Exhaust + OAP sounds beautiful, but not at this rpm range...I intentionally have to use manual mode to keep the rpm range above 3k just to avoid this drone.

BTW, I have Soul Valve controller and it works like a charm with the best value compared to other products!

pitt911

thanks, for the info I have the same exhaust and reducing the drone in that rpm range by 50 % sounds great

sehyang82

I'm curious about this as well - gotta take it out for spin tonight to test.

Westcoast

I have found that I generally run the CG controller in Sport when I want all of the glorious sounds, and the Auto and leave the button in the console to off for the quietest running.

Still if pulling the tube and blocking the ends reduces the unwanted drone even more I will be doing this as soon as I find a pair of suitable plugs...

2XIPA

Read in another forum there’s a 7.5 A fuse you can pull to shut off the symposer. Has anyone tried that and noticed a difference between that and plugging it up?

lovetoturn

Plugging the vacuum line for the Symposer and or keeping it's valve closed does remove much of the drone as mentioned above. However, even after doing that, the whole plastic tubing apparatus is still physically connected to the engine firewall. Even if plugged, it will still transmit some vibration and sound through into the cabin of the car.

When doing audiology testing on a patients at the doctors office, one can use a tuning fork to help determine a persons level of hearing. The doctor can rap the tuning fork and it will resonate for a while and its sound will slowly decay over time. When you put it near a patient's ear they can hear it for a certain length of time. If you then touch the end of the fork to the patient's mastoid bone just behind the ear, the sound will last a little longer and be a bit louder. This is because the sound is mechanically transmitted to the ear through the vibration of the skull and not just through the sound waves in the air.

So disabling the Symposer valve will help reduce the drone by inhibiting the transmission of the sound waves into the cabin. There will then be a further reduction in the vibration or resonance transmitted into the cabin if the Symposer is physically disconnected and removed. So everyone appears to be correct in their observations, and this should help explain why. So we have a good, better, and best type scenario here.

Look forward to John's OEM type parts to do the job.