How to tell cat needs replacement?

[Cobra^R]

Well, next week im getting a new muffler installed (keeping stock piping & taking off resonator). This car has 90k miles and looks like it has the orginal cat. Being it has 90k miles, would it be worth swapping cats while we are down there? I know my setup isnt extreme but if i do replace it, would it hurt anything throw a magnaflow high-flo cat w/ the stock piping? ($55) Anohter sign i noticed is my MPG isnt the best either, someone said that cat could be a small reason and a new one would help.

Just dont know if theres anyway of telling if the cat should be replaced

[flyinfreak]

Turn your car on.. go under the car.. stick your nose next to the cat.. if you pass out... change it.. LOL i'm just playin. IMO change it. For an extra 55 bux i'd do it even if it wasn't leakin

[tenspeed]

A bad cat will give off a rotten egg smell. It will also throw a code if you have a downstream O2 sensor. It may not pass a emmission test if your state uses it for yearly inspections.

[AMRAAM4]

If you can financially afford it I would advise to change the cat. At 90k you probably have sufficient life left in it on the 3.4L, however, if you plan to keep the car for any length of time the clean cat will provide a nice peace of mind. Plus you are going in for that work anyhow so now is a good time. I'd guess you will notice a slight increase in your MPG and performance.

[Old Guy]

I agree. At this point if you're replacing everything else the money would be well spent. No sense in paying for a second install down the road....

[Cobra^R]

Ok, new cat it i guess. I gotta ask though, am i gonna loose any low end torque or performance using a highflow with my stock piping and no engine mods? Im liking that carsound cat by magnaflow

[Old Guy]

Shouldn't lose a thing, if anything you should pick up a little (and I do mean a little) at the top.

[AMRAAM4]

I agree, a new cat can only make things better. If it is slightly clogged or dirty inside then that will inhibit your performance regardless of low/medium/high end power.

[ecko70]

If it starts peeing everywhere then you know its time to get a new one..

[03xGAxSE]

the way we found out the one on the 93 z-28 was bad- drive at around untill it gets real hot then look at it and if its glowin its cloged, but i thought the cat was supposed to last the life of the car unless clogged if ya want a cat then get one but i would spend the 55 on somthing else thats just me...

[Cobra^R]

Hrm, i got everyone but the cat and im still stumped. From hours of reading, some still say if no heavy engine mods are going to be done, using a high-flow cat will loose performance at take off (lowend torque). Then some say i wont loose any performance.

i guess i can see why theyd say id loose torque at take off due to the high-flow, but should i quit worrying and order my carsound (94000 series) and see what happens? I jsut dont wanna use any torque being im not planning engine mods due to the mileage.

sorry for sounding like a nag :(

[Blackrider]

Mine got so glogged I couldent rev over 3500 I couldent get it over 80KPH.

[greengt]

I say gut it and the hell with emissions!

[bbechtel16]

^w00t!^