Hi all, I'm curious if we can put together a thread of different setups for the CA law i.e. which exhausts work with stock manifolds, catalytic converters, etc. A rule of thumb so to speak would be helpful too. You guessed it haha I myself need to redo my exhaust work. I have:
stock headers to
stock catalytic converters to
I believe it's called dual resonator pipes
then dual catback exhaust and tips

So, I'm trying to see what other configurations we can get that would keep under the 95 decibels limit. I get this is a long shot, but I think it would be worth it so we can get the aftermarket stuff while maintaining legal limits. Any ideas or help would be appreciated.
Pictures are similar to what I have, just a Google photo.

From top to bottom of image, Catalytic converters, resonators, piping, catback exhaust

 

I think this is a great idea so I've moved it to the Intake & Exhaust sub-forum. If it takes off I'll sticky the thread at the top of that SF. Thanks!

 

Liberal California can make laws pertaining to everything possible but to make them work they must be enforced! I can't tell you the last time I pulled up to a stop sign and there wasn't someone on either side talking on their cell phone! As long as you're not running FART CANNONS (honda exhaust) and retain the factory cats you shouldn't ever exceed the legal db's!
Gary

 

Yeah, if your car sounds stock when cops are around you'll be okay.

 

I ordered a Decibel Tester so I'm curious what it's going to say since everything is different passed
​​​​​​passed the catalytic converter. Should be here in a couple days.

 

So even though I'm way over here near the right coast, I'm wondering when anyone is going to post up their exhaust set-up as proposed by the OP.

I'm interested because when my OEM exhaust/cats need replacement, I want NOT loud (a requirement for marital preservation), no rasp or drone (like OEM), better breathing, and slightly deeper tone.

Yes, I want the unicorn.

 

I wouldnt mind checking my car with a DB reader but don't know anyone local that has one.

Stock header, Stock cats, Stillen Catback Exhaust (https://www.stillen.com/2003-2007-in...wall-tips.html)

I honestly think stock has more sound to it.

 

The dB meter applications for your phone are actually pretty decent in that range. They're pretty much garbage for anything over about 105 dB because the microphone just isn't good enough.

Not calibrated obviously but it'll get you a good idea of about how loud things actually are. The trick is don't hold the microphone directly in the airflow of the exhaust or it picks up the sound of air blowing on the mic. Hold it off to the side of the exhaust and have someone else rev the motor.

 

Those $20 sound meters on Amazon work just fine though, when our lazy safety guy at work kept giving excuses for why he was having trouble getting us one I ordered one myself (because I'm wormy like that) and it gave the exact same readings as the $500 one he ended up ordering.

 

Doesn't work. Everything has a wee bit of drone.





OP, I have a top speed pro exhaust with stock cats and it's quiet af. My old motordyne setup with ART pipes woke up people down the street though, it was too loud.

 

I've got the Decibel Tester and it's supposed to be accurate of +/- 1.5dB. According to what I found online, the rules of the test are as follows:
​​​​​​
****Exhaust must not be above 95dB
-Engine warmed up to operating temperature
-The tester must be centered on the exhaust
-The tester should be 18 inches away
-Tester tip should be angled at 45°
-Engine revved to 2500rpm

So I just tried it on my buddy's Subaru WRX and he idled at 101-102dB but that's without catalytic converter. At 2500rpm he was touching 112dB.

We tested my G35 with stock headers, stock catalytic converters, on one side, idling at around 77dB and about 88dB at 2500rpm. I can get a video if someone wants to see how this is done. But good news is I passed. My exhaust sounds like **** and I want to replace it anyways. I'm curious what high flow cats would sound like 😉

 

If you're looking for something custom:

It's stock cats to a used HKS rep with new 304 SS flex pipes going into a Magnaflow 11386? X-pipe. I ran that setup for almost a year on my daily G but eventually got tired of the drone up hills and between 2500-3000 RPM, so I had Totalflow straight thru mufflers welded to replace the rear fart cans. There's still a bit (much less) of drone at 75 MPH but it's possible to drive it (shifting at 2300) so that it's silky smooth and quiet. Still growls at idle (deep done) and screams at WOT inside the car (not sure how loud it is outside)

 

I need to replace the resonators with chambers like you did. I replaced the HKS clone mid resonators and that helped until it settled in. OEM was best and I forever regret going aftermarket.

 

Which resonators are you referring to, I thought you had a topspeed exhaust not the HKS?

 

TS, the HKS rep. I need to do rear chambers.