California exhaust

whitebird93

Registered User
Hey guys, I was wondering if anyone could point me in the right direction here regarding exhaust / my build. I have a 1993 5 speed that I will be changing the fuel pump on and I figured might as well start on the exhaust once the pump is installed. Right now I have kooks mid length headers on with high flow cats to the stock 3rd cat and stock exhaust the rest of the way down. Now I live in Los Angeles and would like to keep this car smog friendly. As of right now I pass with flying colors. The reason for doing the exhaust is im installing some bolt ons. 76mm maf, 75mm TB, mag powers inlet. 94/5 super charger, 10% over drive, raised top, douple intercooler, 42lbs injectors, and eventually a tune to get it running and driving and maybe some ported heads way down the road. Cam seems out of the question in this build if I want to pass smog. The only reason I mention heads and cam it is because it might change what exhaust rout I go. Engine is a newish long block with ARP studs and felpro gaskets. About 25000 on the engine.

Here are some of my questions.
I was looking at getting the mandrel bent exhaust but do I get the 2.25” or the 2.5”? Should I still run a 3rd cat? If so could I even find one with dual exhaust? If not do I run 4 cats or stick with 2?
Is a resonator even an option? Do I need one?
Mufflers? im not sure where to really start I have read tons of posts on here and everyone runs something different it seems depending on their build.
 
I am not in California, but from what I know, if you start to say "modi...", you will flunk emissions before you get to the "fied". Any of the modifications you listed would technically cause you to fail. Not because of any effect on actual emissions dyno testing, but jsut because of the technicality that it's modified. Technically, it should be failing right now because of the Kooks headers. And possibly because of the high-flow cats, unless they are CARB certified. So don't do anything that will draw attention to the modifications, like install shiny chrome parts in the engine bay.

To answer your question directly:
- You need to keep the 3rd cat if that is what the car came with. Some of the engine parts are less noticeable, but changing from 3 cats to 2 (or even to 4) seems like you are just asking for a world of legal red tape hurt.
- So since you need a CARB certified 3rd cat, and I doubt there are CARB-certified high flow 3rd cats for this application, I would suggest that you leave the stock back half of the exhaust for now.
- The front half may be fine as is... You might upgrade to 2.25" mandrel bent pipe with high-flow CARB-certified cats. But bear in mind that you are on shaky ground with any mods to the exhaust, so you might want to save that money for now.

As for the engine itself:
- None of the mods you listed would actually hurt emissions, unless it was an aggressive cam. You could get a slightly upgraded cam that would pass the emissions dyno. It would technically be cause for a failure, but should be functionally within emissions spec. And it can't be seen from outside.
- The MP inlet, 94-95 blower, raised top, larger intercooler, and injectors wouldn't hurt emissions dyno performance. But they would be cause for a visual inspection fail ... if they were noticed. They might not be noticed, especially if you stick to factory-style finishes. Nothing shiny. Also beware the logo on the plenum ... it might draw attention.
- There is actually a CARB certified throttle body for this application. Looks like 70mm is the biggest currently sold. I think there used to be a 75mm ... not sure if that one was CARB certified or not. If it was certified, you might be able to find one used.
http://www.bbkperformance.com/produ...38l-s-c-70mm-throttle-body.html?car_motor_key[]=1625&car_motor_key[]=1626
- I am not aware of a CARB certified MAF for this application. I think C&L's housing is CARB certified for use on the Mustang of the same year, but I don't think they spent the money to get it certified for the Thunderbird, due to the smaller market. Again, you might be able to have this without drawing attention, but the technicality is against you.
 
- I am not aware of a CARB certified MAF for this application. I think C&L's housing is CARB certified for use on the Mustang of the same year, but I don't think they spent the money to get it certified for the Thunderbird, due to the smaller market. Again, you might be able to have this without drawing attention, but the technicality is against you.

I'm in California, and while I haven't yet brought my bird out here with me (It remains in VA for right now) I have had to go through the SMOG check with my truck and my wife's car. My truck is never an issue since it's stock. My wife's car however is considered "modified". It's a Lexus IS 350 and the only "mod" is a F Sport intake kit (air tube and redesigned filter box). It is CARB certified and has a sticker under the hood citing the number that allows it. Each time it gets checked, there is an additional fee involved (Modifed vehicle fee) for which the technician must go into the database and make sure it is allowed on that specific year and model car. If it's not on there, it's and automatic failure regardless if your car emits pure steam and oxygen out the exhaust or not.

Even if the throttle body fits and is the same, if it's not certified for your year/model car it's a no go. Meaning the manufacturer might have paid for the certification for a 1990 model, and if you put it on a 1991 and they didn't pay for the certification that year it's a failure. It's ridiculous in my opinion. The tree huggers won this round.


As for your cats: I did some reading on this when I was considering bringing my car to Cali. My car is a 1990 5 speed. From what I can find, the 5 speed in 1990 has 2 cats and a resonator along with an EGR. The Auto of the same year has 3 cats and no EGR. I'm not sure how to fight that fight if the tech tells me I'm missing a cat.

Also I replaced the cats on my car with the Magnaflow ones (stock replacement style) long before we ever considered moving to California. In my research, if you're in CA, you cannot replace your cats unless you have a certified failure because of the cats, and then you can only replace them with CARB certified ones stamped "Legal for sale/use in CA"

It just seems like a whole lot of work/red tape to wade through for every little thing. I wish that the only check they did was sniffing the exhaust to see what you're pushing out into the atmosphere. This is the end result that should matter in my opinion. No matter what mods you do, there shouldn't be a visual part of an inspection for the SMOG check.
 
It just seems like a whole lot of work/red tape to wade through for every little thing. I wish that the only check they did was sniffing the exhaust to see what you're pushing out into the atmosphere. This is the end result that should matter in my opinion. No matter what mods you do, there shouldn't be a visual part of an inspection for the SMOG check.

I agree. Either do the CARB exemption orders for parts, and visual check (with plug-in for the newer cars) OR do the dyno sniffer test. Doing both is a little much.

You might have some issues moving your Thunderbird to CA, due to the cats. I understand that the CARB certified cats are really pretty much the same, except they have more material to guarantee longer life. At least there is some kind of stock 3-cat option out there for you to find, if it comes to that.

I can say that non-CA 1990 auto cars had only 2 cats, and no EGR. But the CA auto cars may have had the 3rd cat.
 
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the current exhaust i have i did before i moved to Los Angeles. It passed the initial DMV inspection and has passes everyother smog test since 2008. So im not worried about my current set up. If it can handle the mods im doing then i would rather not change it. my intake side i would have to cheat that for sure.
 
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