Exhaust laws in CA...
 

Curious.. I seem to remember some sort of law in this sunshine state that the outlet must be behind the rear axle. I am considering a way to do a turn down by the transmission, but make it look at least semi-legal...
Weight's a bitch and that exhaust is a lot of metal. Maybe a hollowed out cat bolted to the downpipe (for visual reasons if pulled over) and then a turn-down pipe bolted to that.. but is that just no way ok?
-Ryan

the laws here are a bitch. I have yet to see a miata get harrassed by the po-po's though. I'm sure as long as its not ridiculously loud you will not catch any shit for your exhaust proposal. I've been out with big groups of cars that were driving like assholes and got surrounded by cops and harrassed. One of the cops came up to me and asked "wtf are you doing here?" I replied with "just passing through officer"......he let me go with a " dont drive anywhere around these racer kids, they are nothing but trouble":giggle:

It does not have to exit behind the axle.
You are only allowed to change the cat if it fails.
You are allowed to change the catback but it must meet sound requirements. Not sure if you have to have a muffler in place, but I want to say that is a requirement.

That being said, I've driven around with straight headers with a big block 396 and wasn't harassed.

Anything pre-cat must be CARB certified
Cat can only be changed if it has failed
Catback is open, provided it doesn't exit on the side and it meets sound requirements (95dB).

You must have at least one muffler in place as well.

Hmm perhaps a 6" glasspack can = a muffler... haha. Is that 95 db at idle or 95 db at wot like a race track? I think this could be done... but I want to remove the exhaust and see how it sounds before I commit. Unfortunately, my car toes the line with looking like a 'ricer'.. I've been asked to pop the hood only twice in the past 3 years but on the chance that it happens again, I don't want it to be stupid loud all the time..
-Ryan

The fact you have had your hood popped EVER, is a bad thing.
In the last 4 years, I have never had my hood popped, and have been driving modified cars the entire time. I also have been pulled over/ticketed more than anyone I know.

years ago the wording of the vehicle code was " adequate muffler required "
I'm a minitrucker as well and the cool thing back in the day out there was to run a straight pipe and megaphone so naturaly we would get pulled over all of the time. I'm not sure if the wording has since changed though. you can actualy go to a CHP office and they will show you the code.

so the process would go like this:
act like idiot, get ticket.
go to CHP barracks and get tested (back then testing was at idle) and hope they don't ask you to rev it up.
if they did and you failed return the next day for another test, but this time you will have drilled a small hole about a foot inside of the tail pipe and proceeded to shove a bit of steel wool up the pipe holding it in place with a nail through that hole. of course you do this about a block away cause it makes your car run like shit.
get tested again and pass even when asked to rev it up.
get lectured for driving a dangerous contraption and ruinig your truck( thank you officer, yes I understand have a nice day sir)
pull out nail and leave shooting a sometimes firey wad of steel wool out of the pipe.

the code has allways been very open to interpretation. so in short what you can get away with depends largely on the officer that pulls you over and how bad of a day he's had before some idiot went blowing by him at 12,000 rpm and 190db

Haha, thanks for the input guys. For the record, I rarely do stupid stuff on the public roads any more, and both times I was asked to lift the hood I hadn't been flying by at 1200000 rpms...

First time was quite a while ago - I was doing 75 mph or so in the slow lane just flowing with traffic and next thing I knew I got lit up - the cop said I just happened to be the one he picked to pull over since quite a few people were going 75. Once I was pulled over and he saw the car he asked me to show him under the hood. I was N/A at the time and he gave me a funny look when he asked if the header that was wrapped in header wrap was stock and I said absolutely. He ticketed me for the 75 in 65.

The second time was a few months ago - a motorcycle CHP was sitting on the side of the road by an intersection. I was stopped at the intersection in a row of cars - I was maybe the third from the front. When the light turned green and we proceeded through the intersection he clearly intentionally pulled out behind me in front of the car that was behind me and pulled me over. He claimed that black smoke was coming out of my exhaust and so he pulled me over because that signified to him that my car was 'hopped up'. My car has never excreted any black smoke except for when I had a bad tune and was running 10:1 A/F in boost and that only did it when I floored it. I most certainly gaurantee I did NOT have black smoke coming from the car while I was sitting in traffic next to him. He just wanted to find out what was done to the car. This incident was the reason I just went through the fiasco with the CA smog Ref - I didn't have the CARB sticker for the turbo to show the CHP so he gave me a ticket for the turbo and told me to sort it out with a ref.

So yeah, I guess my miata is not so low-key as most / some of the cops here don't know what REAL crime is...

-Ryan

I see your sig pic. You are right, that isn't low key. But it looks good. :)

Florida is the sunshine state, pal.

California is the fascist state.

you're from neither so whats your point?

Just wondering how much the cops really know I have my CARB sticker for a greddy kit but they only thing from the kit is the turbo. Do I have to worry if a cop asks me to "pop the hood"?

Put exhaust on your shit. Don't be a ricer. Exhaust ain't that heavy. Turn up the boost if it worries you.

O ya I ran with the short cherry bomb turn down for awhile and its fairly loud, never got pulled over for it though. and it doesnt sound that good, but definatly cheap.

California is a big state. How the CHP views your car depends on where you live. In Los Angeles, no matter how much I mod my car, it will still be just a Miata. As long as I'm surrounded by the legions of modded out Honda/Acuras and the countless run of the mill Bimmers, Ferraris, and Lamborghinis, the police will always have bigger fish to catch and fry.

that is VERY true.

Maybe with the budget crisis they will cut out the EPA:)

Pat, every time someone mentions weight your answer is to turn up the boost instead. No offense, but while that works for a street-only car, truth is an NB is a pig compared to a properly lightened NA, and 4,000 hp doesn't change how much weight the car has to fight when cornering and braking... as I am constantly trying to find the next thing to gain the upper edge in races as everyone's miatas continue to get faster and faster, clever weight savings are often the decisive factor.
-Ryan

You are fine. I specifically got my ticket for the turbo because I did NOT have the sticker - if I did have the sticker I could have had any turbo I wanted and the cop would not have known the sticker. Now that I have the sticker as well as a copy of the referee's certification in the car, I have no worries about trouble from the po' for the turbo, weather they ask me to pop it or not, regardless of the fact that I too have nothing but the actual turbo and manifold
left from the original kit.
-Ryan

sweet thanks man.

Agreed, that's my general answer. ;) And indeed it does work on a street car. I find it hilarious when people remove the carpets and stereo out of their daily driver to save 20 lbs.

If you race though, I see your point completely. If you want to be competitive, you need an edge wherever possible. If that's the case, the best parts are often not bought, they are fabricated. In this case, you could build a light weight exhaust system. In fact I started to mention this in my previous post, but I've got a feeling you are looking for "where can I buy a PNP exhaust" rather than the best. The best will not be bought anywhere. You'll have to build it yourself or have a fabricator build it. Something like thin wall stainless would be light and durable. I built my exhaust. It's about as heavy as the stock exhaust, but it's all 3" and very quiet.

I dunno about NB's being a pig though. My base model is 2200 stock IIRC, and around 2150-2200 right now turbocharged. I haven't done anything too radical by any means. Still carry a spare, still have all the creature comforts, etc. NA's aren't that much lighter....

FWIW, I ran open downpipe for a while, it was too loud for my taste but not unbearable. I bought a 2.5" resonated testpipe for a 93-97 323/MX3/626 off ebay for $7 and it bolted up perfect. It really quieted the car down a lot. Our local autocross is pretty strict w/ sound limits and I didn't have any problem. It wouldn't pass a visual check for a cat but might keep it quiet enough that you wouldn't get harassed in the first place.

Link to testpipe: eBay Motors: 93-97 323/MX3/626 Racing High Flow Cat Resonator 94 95 (item 120362683353 end time Feb-11-09 11:46:29 PST)

I have no affiliation w/ the seller, but quality seemed good and price is excellent.

Pat - I think the two big reasons I am considering the idea proposed in this thread are that first, no pipe is going to be lighter than any pipe, so eliminating as much as possible seems ideal, and also that for myself not only are my goals DIY but also to spend as little $$ as possible. In some areas this cannot be done and I gladly accepted the cost of getting the proper part - my mspnp for example, but in this case, grabbing a spare cat and hollowing it out completely and then welding a short 9" straight through cherry bomb muffler and turn down to that would cost a total of like.. 50 bucks, and it (I think) should perform as well if not better in terms of spool and power output than any full exhaust. And that sounds good to me. I was thinking the NB's were more in the 2300-2400 lb range, but I've been wrong once or twice in the past...

pdexta -thanks for that idea. On that note, does anyone have any input on wether these resonated straight through type deals with all the little holes inside has any negative effect on airflow through the pipe for a turbo compared to just say, a pipe? The glasspack I am considering has this same resonated design.
http://209.200.64.237/images/auto/6756.jpg

-Ryan

nope it won't hurt flow. unless it's smaller diameter than your DP or you stick your weiner in it.

too bad.. I so enjoy the hot exhaust gas 'blow' job

OK, pulled the exhaust and cat off and drove around open downpipe...

NOPE! That's not going to work! Hahaha it is wayyyy too loud and the whole car vibrates all the time. If this was strictly a race car exclusively for the track it'd be dope...

Ok, so I am going to try to find a cheap as hell aftermarket cat in 2.5" in/out for the miata - does anyone have a suggestion on where to get one? Cheap as hell b/c then I won't feel bad gutting it...

Then I'm going to get flanges, a glasspack, and a turn-down tip from summit and weld this all in the order of downpipe -> cat -> glasspack -> turn down right before the rear axle...

-Ryan

Ya summit usualy has some really cheap ones in any configuration you want. Ive got a 3" and it doesnt seem to dog my spool that i can tell.

That's a resonator in the picture. A glasspack will dampen sound waves more than a resonator but they only last 1-3 years. I have 3 very long louvered glasspacks under my car for exhaust pipe, and then a straight thru magnaflow muffler. I cranked the car and ran it a few times with an open downpipe and with 3 glasspacks only. The glasspacks alone probably reduce the volume you hear by 20%. That's some, but not a ton. I mean, just a piece of pipe to the rear where the glasspacks stop would help 8% probably. So they're worth it for me. Main reason I used them is because they filter out higher frequencies more as to make it less raspy. My exhaust is very very deep and "different" than your typical 4 cylinder. But the magnaflow works very well. It makes for a larger noise % reduction than the 3 glasspacks combined. I never would have believed that until I saw it, but in my case, it's true.

There's a lot that can be done to make exhaust quiet. Turn downs often make it louder. You want at least 1' of straight pipe before it exits for maximum quietness.

But you can't have it all. You want quiet, cheap, easy, simple, light. You don't get that many choices.

lol I just don't want stupid loud - but loud is ok... quiet I don't need. You said you want 1' of straight pipe before it exits - do you mean after the muffler/glasspack or whatever? I think I can work that in just fine. The cat I'm lookin at is 12" long, then the glasspack is 16" long and then I can do about 12" of pipe before the turn down before the rear axle.

-Ryan

here's what I used to do. make a test pipe with an old cat from the junkyard. don't waste your money for a new one. cut the flanges off. beat a piece of pipe through the fuckin thing that is the right length and weld the flanges onto the pipe. you don't have to gut it cause jamming the pipe through will take care of that.
mix up a good solution of brine(realy salty water) and spray the thing down. this helps to make it rust and cover up your fresh welds. esier to pass a visual that way. I accept no responsability for this though. do it at your own risk cause the fine is pretty heavy if you get caught.

I've found everything I need except for flanges. Does anyone know where I can find a 2.5" flange for a decent price? Summit has no flanges.. the downpipe flange has ~3 1/8" from center of bolt hole to center of bolt hole.

V-bands > flanges. I know you want cheap, and I'm 100% for cheap. But I HATE flanges for exhaust pipe. FWIW, if you're trying to connect 2 pieces of pipe together, they make these cheap band clamps. Picture a huge hose clamp/ t-bolt mix that clamps over both pipes and when you tighten it, they're connected and sealed. I got one at the end of my downpipe where it connects to the rest of the exhaust. Works great, no leaks, no warping, no stipped bolts, etc. And the clamp was like 7 dollars on summit racing.

The v-bands are 3-peice kits, am I correct in assuming you weld one of the connectors onto the ends of each of the pipes you're connecting and then the clamp fits over the two?

I would still need the 2.5" flange to mate whatever I'm making to the outlet of the begi downpipe.. but a v-band between the cat and glasspack could be possible... I'm thinking maybe just weld the cat to glasspack to turndown and have the only flange be the one to the dp.. welds > v-bands > flanges ;)

i have two things going for me living in california with a modified miata:

i'm a big, dumb-looking midwestern white guy

i have greying hair.

win-win.

Try driving through Irvine in a slammed '84 Rabbit GTi with tinted windows and primer spots, holding a driver's license with a Santa Ana address. Good times.

If you run a cat and a glass pack it wont be to loud I ran with no cat and it was loud but the cat will def quiet that down a bit.

just do a side pipe in front of the rear tire. its carb legal and no worries

how the hell is that legal?

^^Who let the 'tard in?