Hey all:

The actual question is... and yes I know this is probably dumb because of how usable the 4G63 is... can you make 305whp (or even 350) and pass smog in California? Can I do this running a legitimate catalytic converter? I completely understand that regardless, this will likely involve a tune and (afaict) ALL tunes are illegal (COBB?) but!

Is it REASONABLE that I could be tuned with a CARB EO cat and have ALL Carb legal parts, and pass a sniffer test (that they apparently no longer do)? And have ~305whp? And not blow my car up or light it on fire lol.

First, I don't NEED my car to pass smog. But having owned my car for over 15 years, and being in a different life spot than I was when I struggled to cobble together the money to buy it... I'm interested in at least having the discussion.

Second, and possibly relevant, I'm looking into what it takes to actually produce CARB parts for this state. Genuinely unsure if this is the route to go but suffice it to say there would be costs associated with that.

Third... my car was tuned years ago at STM (my tune post is in there) and made 305whp with this mod list:
My car is a 2006 USDM 9 MR. ~48,000 miles. 93 Octane pump gas.
My mods are:
1. Buschur TBE with test pipe.
2. Buschur UICP/mini battery.
3. AMS LICP.
4. DW301 Fuel Pump.
5. Vibrant Cone Filter (no airbox).
6. Hallman MBC
7. AEM Wideband and Boost Gauges.

I've since added a megan o2 housing and a toxicfab manifold, but basically nothing else.

I'm really happy with the power that the car made, and would be happy to have it pass the sniffer test which I believe I can make it do fairly easily. However... passing the visual is more challenging.

It seems that the only 2 intercooler pipes that have CARB certs are Mishimoto and Injen. I already have the small battery. Injen seems to be more stock routing, and honestly I don't love that it has the intake included. I still use the stock snorkel and just a vibrant cone and have been content with that. It's also gonna be going backwards a bit on performance? Does anyone know how the Mishimoto setup is? Is this also short routing? Is it even comparable to the other stuff (mind you, basically all of my mods are 15 years old)?

Exhaust is going to be more complex. The factory cats are NLA and it seems that there are a handful of "universal" carbs that are CARB EO'd for our platform. These would be original diameter (2.5?) and would have lots of restriction. I also sourced a NOS downpipe from the UK which is also going to be significantly restricting.

What I'm asking is basically up top. Because I'm rambling.

What does a reasonably legal CA build look like? We all love cars, and love building them... to me, this is no different than trying to work within the rules of FIA or F1 or NASCAR etc. We have the rule book... what can we do with what currently exists, and what parts would be really nice if they exist.

Additionally, if there are any people who have actually seen data from SMOG or via CARB testing, I'd love to talk. I just had a call with SEMA yesterday about the various ins and outs, but always nice to get more data.

Also hello again Evo M lol.

 

First off, welcome to Cali. It's nice but as a car enthusiast it's a big frickin hassle. To answer your questions:
1.) When you go get your cam smogged they will not put it on a dyno or even do a sniffer test. Instead, they plug into the OBDII port and check the ECU for any tunes. Every time your car is tuned, the ECU changes the "CVN" code and the computer they plug into your OBDII port is comparing the CVN in your car at the time of inspection against a known database for the CVN for your car. If the CVN is different then they know the ECU has been tampered with and you fail smog. Think of a way that you can keep your ECU unmodified at the time of test but still have your car tuned for more power and you have the solution you're looking for. I'm not quite sure how this will work since you're essentially importing a car into the state that already has a modified CVN. During the smog check they also pop the hood and look for any aftermarket parts. If they see aftermarket parts they will look for a CARB EO sticker. No EO sticker then you fail the test. If you fail (or if you're bringing your car in from out of state) you may have to take it to a Referee to get looked at. The ref is a senior mechanic and is trained to really look over your car to find any issues. They can be real dheads.
2.) Most people mod their car and then every 2 years return it to stock for getting smog tested. Pretty damn simple Evo VIII and IX to change out a cat, downpipe, intercooler pipes, and intercooler.
3.) You're correct, the CAT Converter is no longer available. Walker makes a CARB Approved 2.5" diameter replacement that you will have to get welded to the right length with the correct flanges and provide that paperwork when you get the car smogged. This will likely prompt the mog tech to start looking over your car with a fine tooth comb for any OTHER mods. If they pass a car with mods they can get big fines. One thing to note is that a friend of mine with an IX in SoCal ran into a problem where he was sent to Ref and the ref looked at his completely stock CAT and continuously failed him because the CARB system doesn't recognize that the IX has a secondary O2 in the Catalytic converter. The carb system was setup to only recognize the VIII that doesn't have an O2 in the Cat. My friend took printouts from the service manual and documentation from Mitsu dealers showing that the IX has a 2nd O2 and the Ref still wouldn't pass him. Friend ultimately had to install a VIII cat and leave the second O2 tied up and stowed in order to pass the ref. Pure stupidity due to the IX being a 1 year wonder. Note that if the smog tech or the referee determine that your CVN is different than stock, you may have to take the car to the dealer to get the ECU reflashed with the original code to put the CVN back and take a copy of that paperwork from the dealer to the smog tech or referee for review to prove that the CVN on the car matches from dealer.
4.) It's prohibitively expensive for a new part to get CARB EO approved. You have to do tons of expensive testing to prove that the modification doesn't negatively affect the pollution of the vehicle. This pretty much means that the mod can't really add that much power. Who buys engine mods that don't make more power? That's pointless. You could make a part that spits virgin white kittens out the tail pipe and gets rid of all the smog in the world but if it doesn't have a CARB EO number they won't let you pass smog.
5.) An alternative to all this is to register your car out of state and then you don't have to deal with smog at all. Very easy to do if you're in the military (most military keep their stuff registered in Florida). If you're not in the military you'll have to setup a Montana LLC which is pretty cheap. Unfortunately Cali DMV is now working directly with the Montana DMV to catch and prosecute people for it. They're going after people who buy exotic cars for tax evasion (not necessarily smog) because registration fees and taxes on cars is very expensive in Cali compared to Montana. There may also be vehicle insurance implications to doing a Montana registration if the insurance company discovers that you live in Cali full time.
6.) Not every county (or even every part of every county) requires smog testing. People sometimes buy a house in the mountains and keep their project cars registered there.
7.) Even having stuff like a wide band gauge and boost gauges will prompt the smog techs to look over your car with a fine tooth comb.
8.) You can pass with a cat back exhaust, fuel pump, and mini-battery. The Upper IC Pipe and Filter will not pass and will prompt them to look at your intercooler, LICP, downpipe, O2 outlet, and manifold and you'll get failed. CARB basically wants a completely stock car.

 

FSAE:

I think you're telling me things that I already know. Having the additional anecdotes about the Evo 8 cat is good intel though.

The other thing I want to question is about that CVN number. I was aware that any tune is problematic, but my assumption was that you could simply reflash back to stock to go and get smogged. I'm aware that this would be illegal, but I'm not fully certain of your claim that the ECU logs a different checksum variable each time it's tuned and reflashed. My assumption (again, respectfully questioning, not specifically stating) was that if I had a tune, which I do, I could simply reflash back to a stock table on my ECU and go get plugged in. If THIS isn't the case, then I have different things to figure out BUT... again, I don't need my Evo to be registered in CA.

I do want to point out that I don't know that the testing is actually "prohibitively expensive" from a business perspective, but there's no question that it would change the profitability of a component. In most of my discussions, the numbers being discussed are $20k and under. I'm VERY early in that stage though and I'm WELL AWARE that there is much more knowledge out there to be collected.

Regardless, I think my question still stands.

What power can be made with CARB EO mods? What is POSSIBLE, in California?

 

I'm in Cali running Cobb for the smog benefit. Im currently on cobb stage 3 that is CARB legal with all their aftermarket CARB legal aprts. I smog on stage 3, then after smog, I swap to my pro tune.

 

Injectors, Fuel Pump and LICP on whatever stock frame turbo that fits the stock air intake (FP71HTA, FP Green, BBK Lite/Full). Power levels on E85 450-400 and at that point I would hope the cat stays together.

 

That's horrible. Evo 8/9/X on COBB is not a good idea. You should get a real tune or you risk engine damage.

 

The pro-tune is a custom tune using Cobb port tho. So it is a real tune.

 

People that are still trying to run Cobb pro-tunes in 2026 are like the adults that want to believe in Santa Claus. From my perspective its unsettling to see an adult lack that much critical thinking skill that they believe in something imaginary is real.