Will a 99-04 mustang gt pass the emissions test with a gutted Catalytic Converter?

It will fail 100% sure. Ive talked to the smog people about exhausts. Anything after the cat is not their concern. You gutted the cat so it will fail end of story. Go find a stock cat for 50bux put it on and get it smoged.

LOL, you guys are funny. If you gut the CC you will still pass the emissions sniff test with no problem and they will hand you your little emissions pass certificate showing all of the gases you are emitting are within the federal guidelines. You will however be taking the chance of getting fined for not going along with the federal scam (EPA) guidelines. Also you should know that under federal regulations you must replace any CC with an exact replacement from the manufacturer or your also subject to the same fine, it's total BS. This whole emission testing is complete BS and I have seen it proven for a fact multiple times with punched out converters. The reason many states had but no longer have emissions testing, is because it was proven in court and the state was forced to quit charging for emissions testing do to the fact a car with a gutted converter could completely pass the sniff test. The whole emissions testing garbage is a complete scam. The guy up there saying you will get no horse power increase is an idiot and knows nothing about engines and restrictions on exiting exhaust in relation to HP.

no, it will not pass the emissions test and there is no reason to gut one, I have had vehicles both ways, and the muffler is what makes it sound good, stock engines do not need high flow cats, or any of that other crap manufacturers sell to young people with these fantastic claims (gain 50 hp instantly, put this magnet in the air cleaner). It does not matter what you do to a cat if you stick a muffler behind it anyway.

And hundreds of people a month ask this question, the removed the cat, threw that o2 sensor in the neighbors back yard, and when the check engine light , along with the missing cat failed the test, its suddenly an EMERGENCY.when the tags are due. I told one young man a few days ago, to put the cat back on and hook up his o2 sensor and solve the problem. He got really angry at me, HEY, I KNOW BETTER. I bought a nice s10 with a v8 years ago, with a new motor it passed a fuel injection based parameters, better than most fuel injection cars, with a carburetor no less, and they FAILED IT. why? BECAUSE IT HAD THE WRONG ENGINE, AND ONLY THREE OF THE 11 REQUIREMENTS. what a pain in the butt. Be smarter than the test. put a real cat on. with the o2 sensor, pass the stupid test. Then go home and take the dang thing off if it makes you happy. Its unlikely the vehicle will pass otherwise, but good luck, there is no penalty for trying and failing, and you will have the proof on paper what needs to be fixed too. If you live in an area with smog laws, either buy a car that does not need emissions. Or make your life less stressful, and do not try to make something illegal pass, that you know it wont.

It depends on how the shop you go to tests your vehicle. I hear sniffers are getting a bit dated and many shops are simply doing visual inspections and checking for OBD-II codes. If that's the case with your shop, you'll just need a set of MIL eliminators to keep you from getting codes (since your car will know something is wrong with the cats) and you should be alright. But if your shop uses a sniffer, you'll fail for sure.

Another option many Mustang (and I'm sure other make/model) owners use is having 2 exhaust system. Remove your current system (which I assume passed) and keep it stored. Then get yourself a new setup with an off-road midpipe (catless) and muffler + exhaust tips of your choice. When testing time comes around, you remove your "good" setup and put the passing setup on. Then swap back once you've passed emissions.

I'm just curious as to why you gutted them... just change your midpipe over to a high flow ceramic cat setup or off road H-pipe depending on your state and county... I checked my parts book and according to its 2009 year scale.. NC doesn't have a state wide emissions test, just a safety test yearly and emissions is county specific.. you could do the high flo cats from Pypes for 189 ceramics or 289 for metallics found at american muscle dot com plus use mil eliminators for trouble codes on the 99-04 models to be completely legal in all states.

And for those that don't know, yes removing the cats on any vehicle does, in fact, increase the sound decibals from the exhaust. because it allows the gases and pressure to move faster through the pipes, which is why it is highly recommended to use a chamber muffler instead of a straight through design to lower the sound volume, because if its to loud you can get a noise violation ticket just as fast as a emissions ticket.

lol it depends on if your friends with the guy inspecting your car and if they sniff the tail pipe. but if you have a little handheld reader that hooks up to your obd2 port then you can reset the code right when you get there and no code will spit out before a few miles. but as long as you have the cat on there gutted or not and they cant see the welds or where you have cut it apart then you should pass if there are no codes when they hook up the tester to your car.

Pffft. NO! Unless you have a little knowledge and 8 bucks.

Not a chance in the world.