Hello to all,

I've recently traded my Cayman S for a 2007 GT3. The new car has a sharkwerks bypass and sounds absolutely fantastic. The original muffler did not come with the car and my concern is passing the noise test at LCMT.
I have been attending DE events for the past two years at LCMT and am aware of the 92db sound restriction. My question is will I pass the sound test if I don't use the "sport" setting as the engine sounds much more quiet?

I also saw in some older posts the possibility of further"quieting" the exhaust by capping a vacuum hose keeping the lower exhaust flap closed at all times.
Would appreciate your thoughts on this issue..
Thanks

 

I think Bob Rouleau might chime in on this one,if anybody knows the sound rules, he's the one that would be able to answer your question !
One thing for sure is that the 997 GT3's are pretty much borderline ,even with stock exausts ...

Cheers
Phil

 

At the beginning of this season, guys were having trouble with sound, with the same setup they ran in 2013.

 

I'd be worried with the bypass. The Sport setting only makes it quieter at low revs once you get over 4000 RPM the valves open anyway and you get full sound. Since LCMT measure not only on the front straight but at random locations around the track - especially where cars at a max power, I'd be concerned.

 

This is what I was afraid of... What have others done in a situation similar to mine? Thinking of trying the solution offered on the Sharkwerks website, whereby they suggest plugging somekind of vacuum hose which would keep the lower exhaust flap closed all the time - regardless of rpm. Apparently, this reduces exhaust noise significantly and meet the db limit at Laguna Seca (limit of 92db).
Any other suggestions? deflector tip? Short shifting at 4000rpm is not an option!!

 

The vacuum hose trick probably works. Easy to reverse too apparently. I did the reverse on my 996GT3 -always open but returned it to stock because it had too much drone on the road.

 

Thanks Bob. I'll look into this over the winter. Plenty of time to figure something out...

 

You can try a down pipe, this served me well in the past

 

Leave it open and you will DEFINITELY get black flagged!! (unless you lift slightly when passing the sound monitor guy, usually parked on the inside beginning of corner 6)
First hand info here.... I mean offender!!

Bottom line, just plug the actuator solenoid and you won't have any noise issues at LCMT.
Simple solution that's easy to do.... and undo... and you will remain on friendly terms with the LCMT sound police!

 

My 996 GT3 has a stock exhaust and I was told by the sound guy I was just under the limit. This was a day featuring low hanging clouds which makes things worse but even so, it's stock!

 

Thanks Guys, glad to see there are options for me. I only thought about the noise restriction issue after I bought the car...
Peter: when you say to "plug the solenoid actuator", assume you mean the simple mod proposed on the Sharkwerks website (ie. plug the vacuum tube). If so, the solution sounds ridiculously easy!

 

Just follow the link below:

Link

 

Thanks Peter. One last question: where is this actuator solenoid (or vacuum hose as they call it)? Is it reachable from the trunk or underneath the car? Can't really tell from the pictures provided as it's a closeup picture.

 

Dino the vacuum lines are visible when you open the engine lid. Should be trivial to make the change. Open your lid and look

 

Thanks for the help Bob. Looking forward to next spring!