hoops25

Just purchased a new to me 2014 GT3, wanted to post a few questions, and also let you all know that I really appreciated this forum throughout my due diligence and purchase process.

The car came with a Sharkwerks bypass exhaust installed and the stock exhaust in a box. I love the sound of the Sharkwerks in sport mode and am looking forward to taking it to the track in NorCal. Sonoma and Thunderhill should not be a problem with sound checks, but I would like to go to Mazda Raceway Laguna Seca as well.

I have combed through the posts discussing potential sound baffling (busting) workarounds, but wanted to ask the following questions:

Is there a simple solution (chip, vacuum cap) to pass the sound check at Laguna Seca with the Sharkweks bypass exhaust installed?

If not, is there a simple solution (chip, vacuum cap) to pass the sound check at Laguna Seca with the stock exhaust? How much would you anticipate the exhaust swap to cost each time I want to go to Laguna Seca?

Any advice would be greatly appreciated.

Thanks,
Chris

sgroer

I think it's possible to pass sound there if you wire the valves shut. We have to do that to some cars at a track here in Atlanta. It requires some piano wire and about 15 minutes. If you look at the valves it is fairly obvious how to accomplish this. The gt3 with the valves wired shut is in the low 90's db range. Some say heat buildup is a problem (I don't think it is) so do your due diligence and make a decision you are comfortable with.

Jamie_GT3

I'd be careful with 9000 rpm runs and the valves closed, that route through the sides is pretty restrictive, car will pull timing and power to compensate if it sees EGT's starting to climb...

orthojoe

Look up mech33's thread on the Laguna GPS switch. Everything you need to know is there

hoops25

mech33's workaround solution is pretty darn complicated and I don't think I have those skills in me. I appreciate the effort, but pretty sure I would mess something up. I'm starting to realize that if it was easy, I would have found the solution by now or Sharkwerks would have found it as well. Bummer, no Leguna Seca for me!

24Chromium

Just stay far left going up the hill out of T5. Lift off throttle until the braking zone for T6. Then back to business as usual. Just make sure not to brake check anyone behind you!

hoops25

Do you think that plan will work even with the sharkwerks and in sport mode?

And what if I just re-installed the stock exhaust? Would I still need to back off between T5 and T6? Could I run wide open then?

Thanks.

Serge944

The only stock GT3 that passes sound is the 996. For every other GT3, you need to cheat.

Mech33

This. If you're not trying to dial out every last tenth of a second from your lap time, just lift a bit between turns 5 and 6. You can shift early and cruise up the hill and pass sound no problem.

Don't let that scare you from going to Laguna. Overall it's becoming my favorite track up here due to the combination of proximity and consistent weather.

Then again, I'm writing this post from a rainy day at Thunderhill right now... at least the skid pad is open.

MayorAdamWest

I passed no problem by having the sport exhaust off, and shifting under 4000rpm up the hill. That said, be warned, Miatas will pass you. Now I have Mech33's solution, and it's amazing. There were some shops that were going to make several and sell them. Maybe someone will chime in.

Ducati1199

Do you use turnaway pipes in addition to the GPS valve close solution or stock set-up?

orthojoe

You need turnaway pipes in addition to the GPS switch in order to pass 90dB. You can pass 92dB without the turnaway

Mech33

Right. I blew 92 dB with valve mod only, and 88 dB with the addition of turnaway pipes.

Ducati1199

And that's with stock side and center mufflers? As I've removed and bypassed the side mufflers I guess I'll need 10 foot turnaway pipes!!

orthojoe

You removed the side mufflers? I thought you had the center bypass. When did this happen? Might be really close. I think center bypass would still pass. Not so sure about side