High CO indicates you are running too rich. Before I would buy anything, I would look at what the O2s are reporting versus what the fuel trims are doing.

 

I planned on doing both because I heard that running too rich can destroy a cat.

 

Tomorrow im replacing the O2 sensors. What is the stock exhaust pipe size? its 2.25 2.5 or 3inch. I need to find out in order to order the correct cat.

 

Your correct, running poorly could kill the cat but quess what, it could kill an O2 also. Don't just replace the O2s without scanning it. What if you have a condition caused by a bad injector or a bad plug? Putting a new O2 in blindly could only serve to kill it as well.

I thought the single pipe size at the cat was 3.0 inch but just to be sure, put a pipe wrench or other adjustable jaw device on it and then measure the jaw opening. Be careful of OD and ID when purchasing.

Just for grins why don't you ask what a muffler shop would charge to provide a cat and install it? Then ask them what it would cost if you provided the cat and they intalled it.

 

well I ran some STP brand injector cleaner and I changed the plugs. now im in the middle of changing the O2's. One of them was easy but the passenger side injector is giving me a lot of problems. the O2 is mounted too close to the joint where the exhaust manifold meets the y pipe that I cant get an O2 sensor socket onto it completely. I was only able to get it half onto the sensor. .. blah blah blah. long story short, the 02 sensor is beginning to strip and I dont see how im going to get it off. After that, I'll throw on a new magnaflow cat. I'll be doing all the labor myself at my Highschool Auto Shop.

Any advice for getting this stubborn O2 sensor off would really be appreciated

 

Spray it really well with a good rust penetrant and let it soak for awhile. I have good results with PB Blaster. I just used an open end stubby wrench and popped both sensors out.

 

Okay we used some PB blaster in autotech and got the O2 sensors changed out. I talked to the previous owner and he verified that the cat is hollowed out. is there any way to pass emissions with the cat hollow because if I put a good cat on, its going to be quieter and I'd rather avoid that if possible.

 

Nope, if they are putting you on a sniffer test and that cat is hollowed out, you stand no chance of passing. Either go with a stock replacement or look into an aftermarket high flow unit. You stand to gain very little, if any, horsepower by having the cat removed.

 

WRONG it can sound a hell of a lot better with a cat. My wifes Durango has the sound that EVERYONE wants when they hear it. It has the original cat and a flowmaster 40 series. Everything I have ever heard, sounded better with a cat.

 

i would agree with speedygonzales. i run the carsound / magnaflow cat with the magnaflow cat back and i swear it sounds like a nascar on the floor. whoever told you otherwise is just not using the right stuff. don't let sound reduction have anything to do with your cat choice.

david

 

From what Ive seen a stock cat holds back more sound than a stock catback. So just dont go stock.

 

does anyone on this board replace anything performance realted with a stock piece??

david

 

Okay thanks for all of the advice. I think im going to look into getting one of the magnaflow cats that are like 70 or 80. I know one half of those needs to be welded but does the other half bolt on like the stock cat?

 

i had both sides welded.

david

 

Does anyone have the emissions results for a good running, passing LT1?
I'm just curious how the #s compare with my S10's V6, since I'm tempted
to go about a V8 swap in the future. Curious if the LT1 meets/beats what I
must pass in my TBI V6. I'm sure it will, but I'd just like to see #s. Thanks!