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Discussion Starter #1
The cat on my 03 svt went out and emissions is due at the end of March. I plan on fitting the FSWerks Stealth exhaust at some point, but that time and money that I don't have to burn right now, so the main goal is to get the converter replaced to pass emissions. Knowing that I'm going to be going into an upgraded exhaust, anyone have a recommendation for a cat? I'm looking into Magnaflow, but I'd like to get expert opinions.
 

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Regardless of what you upgrade the exhaust to a CAT is still "needed" for all vehicles to be road legal on public roads.

Finding a used OEM CAT on the for sale section or on the face book pages is going to be your best bet. Due to the pipe locations and routing its difficult to fit any type of other aftermarket round CAT.
 

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I just went through the CAT replacement for my 2003 ZX5 and I live in CA with strict regulations. It's illegal here to sell or purchase a used one. I bought one on Rock Auto, the Walker was 1/3 the size and it didn't fit so I returned it, plus it had really poor craftsmanship. Bought a Magnaflow that was well made and it didn't fit either, and it was 2/3 the size with a relocated downstream sensor location that was placed after stage one and before stage 2, in the middle of the CAT. I ended up keeping my original Ford CAT and decided to do more research on them.

The original CAT on the 2003 SVT was rated at 150K miles and 15 years of use. If the insides or the ceramic cores are not loose and the entry comb looks to be intact, I would consider cleaning it first. Just take it off, inspect it, shake it, tap on it lightly with a hammer, and clean it if it's in good shape. Just soak it overnight in water and Dawn, or Tide pod, rinse it good with water and let it dry. You can sort of test it, by checking the temp at the entrance of the CAT, and at the exit of the CAT, as the exhaust gases convert, they should rise in temp by 50F to 100F. You can also add laquer thinner to your gas to clean it out as well. Then look upstream for the source of your CAT issues.

The new sleek aftermarket CAT's are mostly designed to last 50K miles and have a 5 year warranty, and are much smaller in size, so there is less precious metals on the insides. Most also added an extra stage of gas processing so they are 3 stage now (2009 CARB compliant). The Magnaflow (2009 CARB Compliant) is very nice, but pricey, a CA company. The Bosal (2009 CARB Compliant) looks pretty good, comes out of Europe. Walker (2017 CARB compliant) is made by Federal Mogul but probably MIC. The DEC/Davico Economy on Rock Auto looks old school and quality to me.

I can see why the warranties are lower now, because many people replace the CAT which is the symptom when the real problem is upstream in the engine.

Things to look for upstream:
Excess unburned fuel will create that stinky smell, gas will flash off in in stage 1 of the CAT, and burn it out if not resolved. Too lean of A/F ratio will overheat the CAT and burn it out as well. You want the perfect Stoichiometric A/F ratio in which the STFT toggles up and down about a unit of 1 but no more than 9. The downstream O2 sensor says rich, so the injectors pulse lean, then toggles to downstream O2 sensor says lean, injectors pulse rich, and this cycle repeats over and over. One of the jobs of the ECU is to provide a perfect Stoichiometric environment to protect the CAT for the lifetime of the car.

In 2003, on the Zetec Engine with the Federal Regulation, your car should be PZEV, and protecting the CAT and clean air was the priority sacrificing fuel economy. In 2004, when the Prius came out, it was ULEV in which fuel economy trumped clean air, thinking that more MPG would reduce emissions in the fuel supply chain, and overall reduce emissions more. So I'm saying your CAT should be rock solid, and look elsewhere in the engine.
 

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I got an aftermarket one from RockAuto, but it broke in a couple of weeks at one of the welds. I've heard that in some states you can't pass emissions unless you have an OEM cat. I'd guess that a good shop could fabricate one. It's significantly different from the regular Focus, but it looks pretty straightforward.
 

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I got an aftermarket one from RockAuto, but it broke in a couple of weeks at one of the welds. I've heard that in some states you can't pass emissions unless you have an OEM cat. I'd guess that a good shop could fabricate one. It's significantly different from the regular Focus, but it looks pretty straightforward.
That's why I return the ones I purchased. The Walker (2017 CARB Compliant) would of broke off because it had no real secure fastening system to the engine, and had sloppy welds. The Magnaflow had the tail end of the pipe stuck into my oil pan. The SVT CAT looks like a universal model could be welded inline to the old CAT's flange and pipe quite easy. Just watch the length so you don't push or pull the CAT back exhaust system forward or back so it hangs straight.

I think 13 states follow the CARB regulations, and 3 enforce the CAT regulation, CA, NJ, NY. In these states it's illegal to modify a CARB 2017 approved CAT; or really any CAT, even welding and a muffler shop won't touch it, But you can fabricate a universal model from what I have been told by a referee in CA.

I don't know what state you live in, but usually, the 3 states should offer a financial assistance program of up to $500 and extend your time out so you can get it fixed and find a solution. On my ZX5, the Ford CAT and exhaust manifold was offered as a kit, so that's why it's $1400. I hear there is a secret stash of them somewhere in the US. Guess you must live in one of these 3 states.
 

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That's why I return the ones I purchased. The Walker (2017 CARB Compliant) would of broke off because it had no real secure fastening system to the engine, and had sloppy welds. The Magnaflow had the tail end of the pipe stuck into my oil pan. The SVT CAT looks like a universal model could be welded inline to the old CAT's flange and pipe quite easy. Just watch the length so you don't push or pull the CAT back exhaust system forward or back so it hangs straight.

I think 13 states follow the CARB regulations, and 3 enforce the CAT regulation, CA, NJ, NY. In these states it's illegal to modify a CARB 2017 approved CAT; or really any CAT, even welding and a muffler shop won't touch it, But you can fabricate a universal model from what I have been told by a referee in CA.

I don't know what state you live in, but usually, the 3 states should offer a financial assistance program of up to $500 and extend your time out so you can get it fixed and find a solution. On my ZX5, the Ford CAT and exhaust manifold was offered as a kit, so that's why it's $1400. I hear there is a secret stash of them somewhere in the US. Guess you must live in one of these 3 states.
No, I'm lucky, where I live they don't have an emissions test so I put in an ORP after the cat broke. Selling it might be a problem, but I love the car. I don't think I'll ever sell it. I don't drive it much and it's in very good condition, never been modified. Maybe far in the future it will end up someone's barn find.
 

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Discussion Starter #11
Thanks for all the answers. I live in IL, which from what I understand is somewhat relaxed with their emissions standards. I was planning on going for a Magnaflow cat, but if it truly doesn't fit I'll look around elsewhere. As for cleaning the current one, I don't think that will work in my case as it has been snapped off and welded back on at both ends, and is probably just on its last legs at this point. As for an OEM part, I only paid 2500 for the car, so a $2000 part is a bit much for my taste.
 

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C-F-M use to have some good options. Not sure if they still have any as they have pushed in a different direction recently. They had a high flow CAT and a "regular" CAT. it was not a californa CARB compliant one but was a 48 States "approved".
 

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Discussion Starter #13
Things to look for upstream:
Excess unburned fuel will create that stinky smell, gas will flash off in in stage 1 of the CAT, and burn it out if not resolved. Too lean of A/F ratio will overheat the CAT and burn it out as well. You want the perfect Stoichiometric A/F ratio in which the STFT toggles up and down about a unit of 1 but no more than 9. The downstream O2 sensor says rich, so the injectors pulse lean, then toggles to downstream O2 sensor says lean, injectors pulse rich, and this cycle repeats over and over. One of the jobs of the ECU is to provide a perfect Stoichiometric environment to protect the CAT for the lifetime of the car.

In 2003, on the Zetec Engine with the Federal Regulation, your car should be PZEV, and protecting the CAT and clean air was the priority sacrificing fuel economy. In 2004, when the Prius came out, it was ULEV in which fuel economy trumped clean air, thinking that more MPG would reduce emissions in the fuel supply chain, and overall reduce emissions more. So I'm saying your CAT should be rock solid, and look elsewhere in the engine.
Thanks so much! We've already replaced or rebuilt most of the engine (or it at least feels like it), and run it through the Ford diagnostics, so other than the stuff we know is wrong, nothing is wrong if that makes sense. We ended up springing for the nicest Magnaflow they made. Unfortunately, the old cat was beyond salvation and now hangs in a trophy case in our living room (pics to come). I think what killed it was the fact that it sat for a few years, and there was both water and animals living inside the exhaust.
 

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I still make them , I dont think anyone makes them for the SVT any more

Tom
 
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