Not that I did but if I did, then what?

[Grubb240Z]

Let's say that I, hypothetically...no, not me - a friend. Yeah, let's say a friend hypothetically got a fix-it ticket that included "modified exhaust" that the cop thought was too loud (it isn't) and needed to show up at the DMV to settle it. If that scenario ever presented itself and if this friend made a makeshift exhaust silencer (that works pretty darned well!), he might have the following question for you guys: "What, if anything is the danger of a substantial increase in back pressure to the engine over a short time/distance?".

He is prepared to stop at a park near the DMV to install said device if it is better not to drive 8-10 miles round trip with the increased back pressure. Otherwise, the plan might be "install - drive - test - drive - uninstall".

[Patcon]

I don't know that it will do any harm. There is not cat to overheat and as long as the car doesn't run lean which would make a lot of heat. It will probably be down a little on power.

Will be interesting to see what some other guys think...

[zeeboost]

I'd say install it and drive it around first, if there is a substantial difference in power (car struggles to get up to speed) then you'd probably be better off installing in the dmv parking lot. If not much of a difference then it should be fine for a short trip.

I've come across plenty of vehicles that had converters clogging up the exhaust so bad that they literally couldn't move (takes a little bit of driving to get to that point though). As soon as the converter was replaced, engine ran great without a hiccup.

Could you not at least insert a smaller tube in the center (maybe 1" diameter) so the exhaust at least has some unrestricted place to escape? That way it'd be a safer bet for you engine and would probably still do a decent job of muffling.

[Zed Head]

45 minutes ago, Grubb240Z said:

 a fix-it ticket that included "modified exhaust" that the cop thought was too loud (it isn't) and needed to show up at the DMV to settle it.

If "it isn't" then what's the worry?  Just show up at the DMV, get your dB's measured and prove him wrong.  If you go through all of that work even though the car "isn't" too loud, then the cop wins.

Beside that if the cop sees/hears you again he's going to work twice as hard to find things wrong with your car.

[zeeboost]

I should add that drilling holes in that center piece of pipe would pretty much mimic how most straight through mufflers are designed. Not quite as cheap as drilling them yourself, but basically something like the pipes in here

 

https://www.amazon.com/Dorman-917-016-Oil-Filter-Cap/dp/B0075MREHI

[Zed Head]

Don't overlook that the DMV people probably see hundreds of guys like you over the course of a DMV career.  Your camouflaged wires aren't going to fool them.  Conning the cops is just a bad idea, in general.  I had friends in high school that used to try it and it was always a bad idea, in the long run.  They spent all of their driving time looking in the mirror.  Add to that that your Z won't blend in to the crowd of other cars and you're just asking for a bunch of problems.

The DMV will probably see that black paint as soot from running rich and tag you as a gross polluter.

[Grubb240Z]

1 hour ago, Zed Head said:

If "it isn't" then what's the worry?  Just show up at the DMV, get your dB's measured and prove him wrong.  If you go through all of that work even though the car "isn't" too loud, then the cop wins.

Beside that if the cop sees/hears you again he's going to work twice as hard to find things wrong with your car.

All good points, guys. I really don't know how the car would do on a dB test - I'm just saying it isn't crazy loud - not as loud as most Harleys or most WRXs or Mustangs in the area. It gets loud at higher RPMs (a bit cammy) but idles nicely. It DOES have a muffler on it - it's just a pretty free-flowing one. A bit louder than a Flowmaster or Magnaflow. I'll try to video it later.

By the way, this "silencer" will be inserted about 10" into the exhaust pipe and held in place with a little screw from the side. This is not an add-on tip. They won't see that paint the way it shows in the photo.

The original reason for being pulled over was the brake light not working. My son was driving. The cop added the missing front license plate and "modified exhaust" during his walk-around. The other two issues are now fixed (more on the license plate issue later).

I wouldn't be surprised if a reasonable cop wouldn't have had an issue with the exhaust. I'm just trying to hedge my bet.

[Zed Head]

If the cop "saw" a modified exhaust and you are hiding your trick piece, won't the DMV still see the same modified exhaust?  If they do, they can probably make you pay a bigger fine, and add one on top.  Seems like a big risk just for the thrill.

Everybody raises their kids differently but this seems like the complete opposite of the other thread about the brake light.  It's a slippery slope.

[charliekwin]

Here are the relevant sections of the CVC

http://leginfo.legislature.ca.gov/faces/codes_displayText.xhtml?lawCode=VEH&division=12.&title=&part=&chapter=5.&article=2.

http://leginfo.legislature.ca.gov/faces/codes_displayText.xhtml?lawCode=VEH&division=12.&title=&part=&chapter=5.&article=2.5.

I would call the DMV and ask what they do to clear the ticket. If they just go out there with a noise meter or send out a designated exhaust-listening guy, it's probably worth either getting a cheap meter from Amazon for $15 or even an app for your phone to give you a rough idea of how loud your exhaust actually is.

[Grubb240Z]

@charliekwin Thank you.  I just looked at the links and looked around online for the exact test procedures. I was getting a little scared that they were going to put the car up on a lift, shine a light in, position a microphone, make me rev it to 3/4 full throttle, etc. But I just called the police department and they said I can just bring the car to their station. An officer will inspect the car and sign off on the ticket, which I will THEN take to the courthouse. I'm hoping that if I do it that way, it'll be casual and they won't do a dB test. I'll let you know how it goes tomorrow...

[Grubb240Z]

9 hours ago, zeeboost said:

I should add that drilling holes in that center piece of pipe would pretty much mimic how most straight through mufflers are designed. Not quite as cheap as drilling them yourself, but basically something like the pipes in here

 

https://www.amazon.com/Dorman-917-016-Oil-Filter-Cap/dp/B0075MREHI

Actually, those look so cool I think I'll put 'em on the OUTSIDE of the exhaust pipe!  

[Grubb240Z]

Update: After visiting the local police department and having them tell me they can't sign off on exhaust - I'd need to go see the CHP, I did just that. CHP officer gave me a little bit of a hard time about my header, little filter on my breather, etc., but he recognized that my '72 is pre-smog and let it go at that. Then, he asked me to start 'er up. After listening to the idle for a couple of seconds, he asked me to rev it a few times. My silencer did the job and he said "Sounds like it should be fine". He signed off on all three of my issues (brake light, front plate, loud exhause) and I was on my way. Whew! 

I'll try to get around to posting a before/after silencer video soon.