im getting a cel that the cat is performing below threshold (bank 1) along with evap system very small leak. im assuming its time to replace (2004, 95k) but just wanted to check here before i spend the money. would there be any reason not to replace it with a high flow?

 

Well the basic test to see if the cat is going back is to stand behind the car and see if you can smell rotten eggs.

Other members will probably have more imput, but I know the rotten egg smell is not good.

 

It could be a bad O2 sensor.

First place to start is the MAF. Clean it and your air filter/replace.

Then check for any intake leaks, re-set ECU... see what happens.

 

replace with midpipe, you never have to worry about a clogged cat again and you get 10 extra ponies

It smells like an *** though