So i've been researching exhausts for my 10 g37s sedan. My main concern is how do you guys pass emissions or are there certain exhaust that will past emissions. my second concern is CEL being on. Between Fast intentions/Stillen so far is my choices. Im confused as to what is needed to get that sound. Do i need a full catback system. Can i just do exhaust only? I really just want it for the sound/look and not looking for any super hp gains. Nothing loud and raspy. But i also want to be able to pass emissions and not throw a check engine light. One mechanic told me as long as i dont change the stock cats i'll be ok with emissions is this true? I read that if the exhaust says for Off-road use only that its not street legal and i'd have to remove it before emissions? I've check ga law and it only mentions db levels and says nothing about street legal and off road use stuff.

 

Welcome to the forum, looks like you've already got some pretty common questions. The answers to most of them can be found in threads dedicated to discussing each of these in details. You can find those threads using the regular or advanced search function in the toolbar.

I'm over in Texas, and after a quick google search, it looks like Georgia has similar laws. I believe Georgia requires a catalytic converter of some kind, as well as a standard OBDII emissions test. If that's the case, as long as you aren't throwing a check engine light, and as long as you HAVE a catalytic converter, you're golden. This means for legal purposes, test pipes are off the table. A test pipe may or may not throw a check engine light, depending on which one you get, the design, and whether or not it was properly installed. However, since that isn't an option if you want to stay "legal", you can look more into that on your own.

High Flow Catalytic converters (cats) are designed to provide some emissions control, but still allow less back pressure and therefore more horsepower. IMO, HFC design is sufficiently advanced that cats are no longer the huge bottleneck they once were. Test pipes will cause your exhaust to smell, and it will be very loud, which doesn't sound like what you're looking for anyways.

It's good you're only looking for sound/look, since that's basically what you'll be getting. Yes, there will be horsepower gains from upgrading your exhaust from factory spec, but it won't be drastic. For big horsepower boosts, either get a different car, or go forced induction on this platform.

"Im confused as to what is needed to get that sound. Do i need a full catback system. Can i just do exhaust only? I really just want it for the sound/look and not looking for any super hp gains. Nothing loud and raspy."

Since I don't know exactly what YOU think sounds good, I can't *really* help you there. There are, however, plenty of member posted videos scattered throughout the forum, and that can go a long way towards narrowing down what you want to get. I'm also a little confused on what you mean by "exhaust only". To me, the exhaust includes everything rearwards of the engine, i.e. headers, cats, y pipe, muffler, and tips. Perhaps you meant Axleback, which would indicate everything rearwards of the axle. That would mean replacing just the OEM muffler/tips assembly. That's kind of a big question. Let's discuss axleback options first.

For just sound, lots of members are happy with Tanabe axle back exhausts. AFAIK, it bolts straight on to the OEM mid pipes and sounds pretty good. Other axleback exhausts probably fit, but check some member reviews to determine sound, don't be afraid to ask for a video. People love showing off their cars.

For a Catback Exhaust, you will be replacing everything rearwards from the catalytic converters. There are many options available here. As far as sound goes, a catback will have more options, since you have all that extra piping in which to clean up the sound before it gets to the muffler. The muffler is the single biggest modifier to sound, though, so don't feel like you absolutely need a catback exhaust.

The check engine light is generated when the O2 sensor in your catalytic converter reads an excess amount of pollutants in your exhaust stream. The most rearward sensor is in the catalytic converters. As far as your car's computer is concerned. one catback exhaust is pretty much the same as any other, so don't worry about "off road" vs "street legal" as far as emissions and check engine lights goes. The reason they may put off road in there is to be able to sell to californians that have significantly stricter emissions testing. Alternatively, it could be because the exhaust is so loud it violates some states' laws regarding how many decibels your car can put out. In Texas, the max volume your exhaust can have is 80-something decibels, I forget exactly. Your state may differ.

Your mechanic is being conservative, legally speaking, a high flow cat is just a more efficient catalytic converter. I don't think it would be illegal to put in HFC's. He is correct though, you won't have any problems guaranteed if you just leave the stock cats on there.

This is the part where I tell you that ANY aftermarket exhaust switching or fiddling will probably cause some amount of deceleration hiss. This isn't the same as acceleration rasp. Do some more research on the site here and figure out exactly how much of either of those you're willing to tolerate and go from there. Personally, I got on the Fast Intentions group buy for my exhaust and I am 100% happy with it. I have non-resonated high flow cats, and 12" resonators on the exhaust. I love the sound, get no acceleration rasp, and still pass emissions with all the breather mods and an uprev tune. There IS deceleration hiss, but that is innate to the VQ37VHR engine, and there's no getting around that if you want to upgrade your exhaust.

I hope that helps, welcome to the forum.

Cheers,
Anthony

 

I have ark exhaust and love it. Not too loud, no rasp. There were some power gains but mainly in the low end and mid range. I didn't change the cats out and I think the sound and tone are perfect "for me".

 

Thanks guys for the info. i'll check out that ARK exhaust as well, but i'm loving that fast intentions sound.

 

A high flow cat is only efficient in flow, they are not as effective in converting carbon monoxide into carbon dioxide, hydrocarbons into carbon dioxide and water, and nitrogen oxides back into nitrogen and oxygen as an OEM.

You will still get a "1970" smell with a HFC.

Thats why its illegal to change them.
You will NOT pass smog with HFCs.
The sniffer will give it away, and those that only do ALDL connections will know by the AFR response.

Anything past the HFC does not effect smog regulations.

 

I see you are from California, you are correct, a sniffer will fail with HFC's, but I and many others have high flow cats that passed inspection no problem. Emissions testing in Texas is only through the OBDII port.

 

Hey, I live in California, Im NOT from California!!

 

Haha, okay, okay, my bad.

 

Cali will not allow HFC's. Aftermarket exhaust is fine especially if it is CARB Legal so that wont be a problem with smogging. I had a full exhaust on my last car and never had an issue. Also, if you want intakes, that will also make you fail visual inspection...again unless its CARB Legal. But if you are not in Cali you shouldn't have to worry about it. LoL

 

CARB does not require a muffler, only OEM cats!!
So anything goes past the cat exit.

 

I know, but I was saying to be 100% safe. Cali still has a noise violation if the car is above 93db. I believe most, if not all, CARB legal exhausts comply with this rule. Granted I have no idea how the cop would measure that but...
Still pisses me off that we are relegated to 93db (which I am fine with) and those stupid Harley's can be heard 5 miles away. Effin rediculous

 

CARB has no noise rules, the California VEHICLE CODE does!!



V C Section 27151 Modification of Exhaust Systems

Modification of Exhaust Systems

27151. (a) No person shall modify the exhaust system of a motor vehicle in a manner which will amplify or increase the noise emitted by the motor of the vehicle so that the vehicle is not in compliance with the provisions of Section 27150 or exceeds the noise limits established for the type of vehicle in Article 2.5 (commencing with Section 27200). No person shall operate a motor vehicle with an exhaust system so modified.

(b) For the purposes of exhaust systems installed on motor vehicles with a manufacturer's gross vehicle weight rating of less than 6,000 pounds, other than motorcycles, a sound level of 95 dbA or less, when tested in accordance with Society of Automotive Engineers Standard J1169 May 1998, complies with this section. Motor vehicle exhaust systems or parts thereof include, but are not limited to, nonoriginal exhaust equipment.

Amended Sec. 10, Ch. 92, Stats. 2001. Effective January 1, 2002.



SAE J1169: Measurement of Light Vehicle Exhaust Sound Level under Stationary Conditions
Publication Date: Jul 1, 2007
SDO: SAE: SAE International
DOD Adopted ANSI Approved Approved
This SAE Standard establishes the test procedure, environment, and instrumentation to be used for measuring the exhaust sound level for passenger cars, multipurpose vehicles, and light trucks under stationary conditions.

Measurements are taken under steady-state conditions. In this respect, this procedure differs from ISO 5130 which includes measurements under the dynamic conditions of an engine deceleration.

This sound level measurement procedure has been developed as a guide for governmental agencies establishing vehicle in-service sound level regulations and enforcement measurement procedures. It is directed at the assessment of vehicle exhaust noise and is not intended to determine maximum vehicle sound levels. (See Appendix A.)

Technology changes have occurred that make the SAE J1169 procedure inadequate. SAE J1169 is a legacy test that specifies 3/4 maximum rated engine speed (MRES) as the test condition. Many modern engines will not allow 3/4 MRES in neutral and/or have fuel cut-off software that prevents the engine from reaching this target. Additionally, the measurement technology of slow exponential time-averaging characteristic is outdated as compared to the fast exponential time averaging characteristic used in SAE J1492. For these and other reasons, SAE J1169 will be superseded by SAE J1492, which provides a continuous measure of exhaust system sound level over a range of engine speeds.




Digital Sound Level Meter : Sound meters | RadioShack.com

 

^^^Again...I know what you are saying but you are just missing my point. What I am saying is that a CARB legal exhaust, by nature of being 50 state legal mainly for Cali purposes, will adhere to the CVC you are talking about! LoL Thats all I am saying. I have never seen a cop have one of the portable mics ever and I have been with friends pulled over for loud exhausts before. And the motorcycles will eventually fall under a noise order as well. I spoke to a cop in town last year and he said that they are trying to get something on the books for regulating how loud they can be as well. Harley's are ridiculous around here...I literally can hear them from miles away

 

month old post here but in Mass our cars can be up to 105 db surprisingly