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I am looking for small mufflers that I can possibly use.  The new CA rules are no more than 95 decibels 3/4 of Power and read at  20 inches from the exaust.  Contrary to what some people say about it not affecting classic/vintage or presmog cars <1975) this is not the case.  The new law changes the penalty from a fix it ticket to a mandatory fine, and a mandatory visit to the state ref and a visit to the judge.  The visit to the state ref puts your entire car under the microscope and even though it does not need to be smogged, it must have all factory polution equipment that came with the motor beign used.  The visit to the judge will settle the case and the fine is 1000 dollars plus all repairs already expended.  

It also shifts the compliance issue from the state ref to the time you got the citation.  You cant get the citation fix the problem, and go to the state and pass then go to court.  You must prove that at the time you were stopped that you were compliant.  The state inspection  is just to prove you fixed the problem, all the required equipment is there and you are ready to go see the judge once they test your car and give you the compliance paperwork..

As stated above, some people think and wrote about it not pertaining to classic/vintage or pre-smog.  Not true. The law reads as such (meaning of) :  .....all vehicles subject to registration in CA are subject to.....no more than 95 decibels at 3/4 of power......when measure at 20 inches from the exaust...... etc.... no exemptions  except for motorcycles, vehicles over 6000 lbs and off road vehicles not allowed to drive on the street.

So, I dont want the hassle, dont care about losing a few hp if need be, howeve I do want a car that is compliant and will not give me legal headaches.  So can anyone suggest a good SMALL quiet muffler that will keep the car under 95 db at 4500 rpm?

My current set up is 6 into 2 into 1x2.5 inch, then splits into two 2 inch, each of which goes to a side slot underneath the side bumper behind the wheel wells.  I am very limited in room since the gas tank is custom made and occupies the entire room underneath not leaving the original space on the left side open to accomodate a muffler.

Any ideas?????  Either 2 smaller mufflers for sides or one flat on the main, or perhaps some insert silencers??????  

Exaust Sketch.jpg

Edited by 240z70
Did not finish earlier posting.

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Can't really help but I don't see how you guys out there put up with the stuff coming out of Sacramento!!!

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8 hours ago, 240z70 said:

Yeah, Sacramento needs money!!!

They won't get it by convincing people it's time to move to another state!

I wonder if you could call somebody like Summit racing and if they could recommend a product line that would fit your need. For me I would go to my locally owned muffler shop and pic their brain for the right product.

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It seems that if CA is doing this sort of thing that companies like Magnaflow, Flowmaster, etc are aware of this and would have mufflers that will meet these standards.

On another note I wonder how many palms Harley Davidson greased to have motorcycles exempted?? 

Edited by w3wilkes

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I tried to see if there was a listing or search function that allowed you to search mufflers by size and decibels. 

I know engines are differrent and so are the sounds they output, but it would make sense to have a baseline of mufflers that instead of a top number maybe they might be listed by how many decibels they reduce the sound.  And then you could have them tested on several engines.   Tier 1= under 3 liter, Tier2= 3 to 5 liter, and Tier 3= 5 to 8 liter engine ( say a 2.3 liter, a 350 engine, and 460 engine). 

You could have reduction in the tier 1 of 50 decibels, a tier 2 reduction of 25 decibels and a tier 3 reduction of maybe 15 decibels, then take an average and that would be the rating on the muffler, in this case a value of 30.  or you could just show it like a wheel size, 50/25/15 and this would be the actual values instead of an average.

I really  thought if nothing else that at least the muffler manufacturers would have some type of decibel rating on their units...THEY DONT or at least i did not find any..  What i did find was "agressive sound", low drone removal, quiet, quieter, louder and whisper, stealth.   Its true that it points you towards a direction, but it does not give you specifics.   If i point East and tell you that you will find a pot of gold in this house but dont give you an address, all you know is that it is towards the east, but that is it.  Quiet or quieter without a value or comparison, does not mean anything.   Is it quieter than a Saturn V rocket or quieter than a mouse? There is a lot of territory there to gauge.

Anyway, I dont want to take chances and spend the money on the wrong one.  I want to know before I buy it if it is going to meet the guidelines and not kill the engine with smothering.

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I told my exhaust shop that I wanted it as quiet as possible without sacrificing much performance. The system is a modified MSA 2.5" exhaust with a center resonator and a Walker Quiet Flow out back. It's perfect in the sense that it does exactly what I want it to do, keeps things quiet on long drives and nothing but intake roar when the mains come in.

 

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Leon, that's the kind of real world testing and result we love to see.

Can you get the part numbers for the Walker quiet flow muffler and the resonator they used?  Then others can duplicate your success. I spent a ton of time on summitracings site going labouriously through the Quiet flow muffler assemblys looking at in/out sizes and placement as well as body dimensions trying to find one that might fit. Thanks!

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Nope.  Even if you do, if you are a CA resident, the car HAS to be registered after 6 months.  Only way to avoid that is to actually not be a resident in CA.

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5 hours ago, zKars said:

Leon, that's the kind of real world testing and result we love to see.

Can you get the part numbers for the Walker quiet flow muffler and the resonator they used?  Then others can duplicate your success. I spent a ton of time on summitracings site going labouriously through the Quiet flow muffler assemblys looking at in/out sizes and placement as well as body dimensions trying to find one that might fit. Thanks!

It's a center-in, offset-out 2.5" muffler. I'll have a look next time I'm under the car which should hopefully be soon. The exhaust was done about five years ago so I may struggle to dig up a part number. A friend (@v12horse) recently had a shop put in a very similar system and may be able to contribute. Another buddy just put in some version of a Hush Thrush and while not as quiet as the Walker, it was suitable for him. I don't have any actual sound level data on these but the Walker is as quiet as it gets, I imagine. I was looking for an in-car video I had but couldn't find it.

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Finally changed the exchaust a while back.  Cut the 2.5 main pipe, added a 1 in into 2 out used muffler OEM for some car.  Dont know what but didnt care.  THIS IS TEMPORARY....All I wanted to do was buy time to find the correct set up and be able to drive the car without sounding like i was running straight pipes (which mainly I was) and keep from getting hassled.  Yep, bought a sound meter and tested the sound and it sounds good....OEM type maybe a little louder, however at 5000 RPMs the decibels are about 94-96 which is a great improvement from before which was about 116 -120 decibles at the same rpm.   The muffler is about 5-6 inches tall, so that killed my available clearance and bumps/steep driveways entrances are a no-no at anything more than 1 mile per hours.   Changed the tires with slightly larger ones, 215-60-15  (posted pictures in the tires/wheels forum if you are curious...car and wheels were dirty so disregard that.)  and when I changed tires, I raised the suspension up.  Between that and the extra tire height, it has about 4 - 5 inches or so clearance on the bottom....Still to low for me...  The long term plan is to find low profile wide rectangular 18 to 24 inch muffler that has one 2.5 in and two 2" out.  I have seen a company that makes some, the muffler is about 2.75 inches high, about 10-12 inches wide wide and 18-22 inches long, but that one seems loud and its very expensive.  Its height was barely more than the 2.5" inch inlet. So I will look to see if anyone either makes one more quiet and less pricey or I may just end up having to make one myself and tig it together...Does not sound like something I would prefer to do, but I do need to have a longterm solution to the ground clearance and the noise.  If I have to make it, it will be with bolt on junctions so that if when I bolt on to the supply, I can measure both height and decibels before i spend the time and effort to make the connection to the read pipes.  Obviously due to the limited room on the Z, it will be under part of the transmission mid/rear area and also cover most of the driveshaft, but it wont really matter because if I have to drop the tranny or driveshaft, I would have to remove the exaust anyway because of the setup it has and by having bolt on connections, it will simplify the removal/re-installation.  I will be looking for a muffler that meets the size/shape requirements but that also has some type of testing on it, whether it is a percentage noise reduction value or a plain tested and will not exceed X-amount of decibels on engines up to 3 liters/6 cylinders at up to XX-amount of RPMs.  But I dont  know if anyone actually does that.. Some of the ones that said they were quiet, i checked their video and they were pathetically loud, with a drone, and some sounded like the engine was tearing itself apart...I know I am looking for gold and I may have to settle for steel, but have to try... Any suggestions/leads on a source for the muffler that might meet the clearance and noise limitation?

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I've not had my noise verified, but it's very acceptable to me. I use both a resonator in the tunnel and a muffler at the rear. 2 1/2" pipe all the way, both in and out. I think installation is the key to ground clearance as I have no issues with steep driveways or gutters.

Resonator - https://www.magnaflow.com/products/10426-performance-muffler-magnaflow-4-round-centercenter-straight-through-performance-muffler

Muffler - https://www.magnaflow.com/products/13216-performance-muffler-magnaflow-4-x-9-oval-centeroffset-xl-multi-chamber-performance-muffler

Pictures;

IMG_20180325_143536029_LL.jpg

IMG_20180325_142646447.jpg

DSC_8698.jpg

 

 

Edited by w3wilkes
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I've got 2.5" on my '72 also.  Mine won't fit up into the cut-out on the rear crossmember/differential mount and is a little low.  I saw your picture and was amazed. Then I realized it's on ramps. :rolleyes:

Beautiful car.

IMG_20180325_142646447.jpg

Edited by siteunseen

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