I finally got to looki into my sons 97' f 150 (5.4 L) exhust leak. I put some sea foam in and looked for the leaks.
Both rear cats were smoking quite a bit.
I'm trying to decide what to do now without costing me an arm and a leg.
If I were to just replace them with straight pipe section, would that screw up the o2 sensors?
I have looked at some aftermarkets on e-bay for about 50 bucks each.
We don't have emissions testing here. By the way, there are 235,000 miles on this truck. Still runs great. I've only had it a bout 6 months. I got it for my sons first ride.
Going to put a flowmaster 40 on it after I get rid of the leaks. Kinda quiet it down to make it louder!
Lookin for any suggestions.Thanks.
bullseye670................

 

a flow 40 with no cats will be very very loud. you do loose a little power by removing cats (due to lack of back pressure) but not a whole lot. kinda up to you. it wont hurt anything.

 

Well if you ever take it to a muffler shop they may say take it somewhere else due to the emission laws. Here in Texas a friend bought a car and didn't see any cats on it but when a State Trooper showed up at the car lot **** hit the fan and we don't have any testing either just safety inspections.

 

With that many miles on the truck, his cats are clogged. I gained tons of power and 2 MPG when I gutted my cats at 115K.

 

You can cut off your cats if you want to, but you WILL get a CEL.
You have to buy/build a set of mil eliminators for the rear O2 sensors. (this will trick them into thinking you still have cats)
You will NOT lose any power or MPG's NOR will it hurt your truck to run without cats.
It WILL make your truck slightly louder/deeper.
Your truck WILL smell like a 70's muscle car at idle, without cats.

 

http://www.killswitchcentral.com/mileliminator.htm

 

That's who I bought mine from, but I would seriously recommend buying the "2 wire" mil eliminators from him. They use an RC circuit instead of his "fancy resistor", or whatever it is.

 

Thanks for all the replys!
Still trying to decide i maybe I should just get the cats on e bay for $54 bucks. I do like the link to the mil eliminators, though. I wondered about that.
When you guys say it will be loud without the rear cats and flowmaster a flowmaster 40, how loud are we talking.
I think my sons looking or a throaty sound not just real loud.

 

It is a deep grumble at idle, and a VERY low "purr" at part throttle cruise. It isn't bad, but it IS noticable. Also, the truck will be noticably noisier on takeoff. Especially with the front cats gone and most notably from outside the truck. My truck has a slight "header ring" to it on heavy throttle and low rpms.... Overall it sounds almost like a REALLY quiet flowmaster.

 

If you remove them,

You will need the MIL as your truck is OBD2.
You will not lose power.
You may notice extremely slight MPG (~1) and HP (~3) gain, again maybe.
The sound will depend on where you have the pipes exit and how large diameter the pipers are. For instance a single side exit before the rear tire 3" all the way will have a nice grumble, but not a mustang sound, more like a dump truck sound. If you do a smaller pipe that will change. Cherry Bomb mufflers are nice in my opinion.
(Someone verify)
Doesn't matter if you don't have emissions inspection. Operating a vehicle for usage on the highway without a catalytic converter is breaking federal law, regardless of inspection requirements. That is your call if you want to risk the law.

If you get new catalytic converters,
Get high-flow ones. They will run you ~70 - ~90 dollars depending.
You will not need MILs.
You are legal.

 

I agree. Gutting cats is "old school". With today's technologies, high flow cats don't hurt performance and you stay legal.

 

Definatley some high flow cats. You lose nothing, and gain performance (slight) and some good sound. Cherry Bombs are kinda a dirty sound if you catch my drift. I had a truck with the Flow 40 on it, and it sounded great. I would recommend high flow cats, and either a magnaflow, or flowmaster muffler. Your son will be more than happy with the sound.

 

Removing the cats are only illegal if they are operating properly. If they are clogged it is not illegal to remove the cats, in Canada anyway and I think its the same down there

 

It's legal here only if removal is immediately followed by replacing them with another set.

You have to put another set of cats in their place to remain legal.

 

cut them off and put on 2 high flows, i gained a lot of sound out of doing that