Somthing broke loose inside my cat, and im not sure what to do. I want to take it off or gut it out but the muffler shop i talked to said it would cause problems with the o2 sensors and my truck wouldnt run right. I have a flowmaster, and i want to keep my muffler just take off the cat. I know it can be done, but should I? the rattle is really annoying and i know im due for a new one. So what would be the best route, take it off, gut it, or buy a new one?

 

You can run without one, just might need to do the non-fouler trick on the post-cat O2, to fool it into thinking the cat is still there. Either cut it out, or, just gut it.

The "best" option would be to pick up a magnaflow high flow cat, and replace it.

 

If you're gonna cut or gut it, make sure the blue lights (feds) won't be testin for emissions in your area. Fed law requires a cat but lots of areas don't check for 'em. But as HeyYou said, a cheaper highflow cat would probably be best.

 

gut it and do the defouler trick, however that will only buy you time! if they do emissions in your state.
if you can do it now buy the high flow.... if you cant afford a new cat around 100 bucks ( you may find one cheaper or more expensive depending where you look) than as previously stated gut it and do the defouler until you get the cash.

 

I can offer my experience...I just replaced my cat because the down pipes were rotted through with little holes I had to patch...anyway it was gutted by the PO.... I bolted on a new magnaflow setup for 185 including pipes ...from the torque monitoring software I can see it has improved my mpg and I have more low end grunt..which some other have claimed too.. for a whopping two days until something else broke that it...
To be fair I did replace my precat o2 sensor... but I never got any codes with the old sensor and I reused the post cat sensor.
I have read in more than one place as well as a video or two that gutting the cat and using the fouler will still usually cause the truck to run richer than normal. and if you exhaust is stock it may mess with scavanging effect since I read it helps with that as well.

 

You can get the magnaflow high flow cats for around 50 bucks on eBay

 

? not the older style ones with the two inputs and one output.... the $185 shipped was the cheapest seller for the magnaflow part# 23285 setup... the single input and output ones start around $80 for the right size input and output.

 

I was lookin at the single in single out, I saw 2 or 3 the other day for 50

 

what is scavanging effect???

 

My 2 in 1 out mag. cat was $68 shipped on ebay. but i jus got the cat, no pipes