[Tim202]

At my local auto-x venue there is a sound limit (93Db @ 50ft). I have now blown sound for the second time. Keeping the exhaust stock, what are ways to deaden the sound? I'm not looking to drill into the pipes or scratch the holy hell out of them. I'm over by 1.X Db so it doesn't need to be much....Oh and lifting isn't an option either.

[checkeredflag]

can't you put it in stealth mode (tour) ?

[ctrlz]

For a temporary reduction in sound, I think you might want to try packing the exhaust tips with something like steel wool. To hold the wool in place, you could drill two picture frame spring clips and hold them together with a screw to make a cross. You can cut this springy steel to size. Push the cross into the exhaust tip to keep the packing from flying out under pressure. You should be able to easily twist and destroy the cross assembly to remove the packing once you don't need it. Maybe some long reach needle nose pliers would help. I imagine it will not take much steel wool to reduce by 1 dB. Just brainstorming here. Never tried this.

[Bad Anvil Garage]

Leave it to Commiefornia...

[crosive]

Originally Posted by checkeredflag

can't you put it in stealth mode (tour) ?

while this might work, I seem to remember reading somewhere that leaving those valves closed while going wot for extended periods isn't good for the motor. stealth keeps them shut all the time, but touring mode still opens them up for wot and perhaps even just spirited throttle.

[MSMYYC]

Originally Posted by crosive

while this might work, I seem to remember reading somewhere that leaving those valves closed while going wot for extended periods isn't good for the motor. stealth keeps them shut all the time, but touring mode still opens them up for wot and perhaps even just spirited throttle.

Might get away with it on autocross however.. depending on the course, not much time spent at WOT.

[ChicagoTommy]

Originally Posted by crosive

while this might work, I seem to remember reading somewhere that leaving those valves closed while going wot for extended periods isn't good for the motor. stealth keeps them shut all the time, but touring mode still opens them up for wot and perhaps even just spirited throttle.

There is absolutely no truth to this statement. Literally millions of cars have been built with restrictive exhausts since the dawn of the automobile with no adverse effect to engine longevity. I swear. I don't know why people make this kind of stuff up.

[iPODFAN11]

Set the exhaust to Tour from the settings page. Lets you "un-sync" the exhaust to the drive mode that way you can have the suspension in Track, but the exhaust in Tour.

Have a watch to see some recorded decibels

Originally Posted by crosive

while this might work, I seem to remember reading somewhere that leaving those valves closed while going wot for extended periods isn't good for the motor.

Lolwut?

[bpang1234]

If you know where the decibel meter is placed...you could have some tips made to shoot the sound the other direction when you go by it. That is what a lot of people do.

[MSMYYC]

Originally Posted by ChicagoTommy

There is absolutely no truth to this statement. Literally millions of cars have been built with restrictive exhausts since the dawn of the automobile with no adverse effect to engine longevity. I swear. I don't know why people make this kind of stuff up.

It’s literally in the owners manual.

[soloknight6]

from what Ive seen people do here at the Qualcomm autox, when their cars are too loud, they use temporary turndown tips like these:



Talk to Ed Hanson of EdHanson's muffler shop. BEST exhaust guy in the business, very helpful and affordable, I usually learn something new every time I see him haha.

Turndown tips will make your car slightly quieter from the outside, but will make it louder inside the car. As others have said, be sure to go to vehicle settings and put the exhaust into tour mode in whichever drive mode you use for racing.

[DetCam]

I typically have my exhaust set to "stealth" mode when I leave the house in the mornings, and one time I did forget to change it for an autocross event. I had everything else set the way I wanted it (nannies off, Mode selector on "Track"). The steering felt right, but I swear it was behaving more like it was in snow and ice mode.
I couldn't tell you exactly what the difference was: cut in power, different throttle mapping, or both... it just wasn't right. I kept thinking there was something wrong with the car and didn't figure out until after my 3rd run that I still had the exhaust in stealth mode. I put it in track mode for the 4th run, and the beast woke up. Granted, my rhythm was so messed up by the previous three runs I didn't do very well, but at least my car was "normal" again...

My recommendation: don't do any performance driving in Stealth mode.

[camaro5]

Originally Posted by checkeredflag

can't you put it in stealth mode (tour) ?

Originally Posted by crosive

while this might work, I seem to remember reading somewhere that leaving those valves closed while going wot for extended periods isn't good for the motor. stealth keeps them shut all the time, but touring mode still opens them up for wot and perhaps even just spirited throttle.

Originally Posted by ChicagoTommy

There is absolutely no truth to this statement. Literally millions of cars have been built with restrictive exhausts since the dawn of the automobile with no adverse effect to engine longevity. I swear. I don't know why people make this kind of stuff up.

Originally Posted by MSMYYC

It’s literally in the owners manual.

High Performance Owner's Manual Supplement

The Engine Sound Management
setting should not be set to Stealth
Mode during track events and
competitive driving. See “Driver
Mode Control” under “Ride Control
Systems” in the owner’s manual.


https://my.chevrolet.com/content/dam...supplement.pdf

n

[IH8WNTR]

Originally Posted by Bad Anvil Garage

Leave it to Commiefornia...

Yeah. Totally sucks doing an autocross course in the dead of winter....