i own a 2004 ex coupe with cold air intake a just resently 'hollowed out the cat' with 3in pipe from cat to custom resonator and muffler ever since i holled out the cat my check engine light came on i took it to honda and they said im throwing the catalytic converter inefficiency code what can i do about this

 

get a new cat. a hollowed out cat will KILL the power till a couple hundred from redline. hollowed cats are a horrible idea. and that piping is too big for your car. i hate to break it to you, but you just cost yourself some money, and all it did was hurt your power.

 

I tried this in another post but, last night I hit my rev limiter and for some reason my check light came on and I dont know why everything seems to be running fine does anybody know were those wires hang were i check my codes.is it under the glove box on the 00'??

 

its by the ecu wiring harness. i think there is a rubber thing that holds a couple of harness's. its the 2-wire one.

 

On an 04 (and probably anything newer than a 96) most cars have an additional O2 sensor AFTER the cat. If it sniffs too many hydrocarbons getting past the cat, because you gutted it, you'll get the light.

Get the wallet out.

 

yeah dude ..3 inch on a 4 cyl??? ouch .. even with an ok cat. still a bad bad idea. if ur gonna hollow out the cat. , y not just buy a test pipe or a hiflow cat.??