its prob a test pipe then

 

ok, well I planned on running one of those "O2 simulator" things that screw into the cat and then the sensor screws into it. Would this work to get rid of the check engine light?

 

Hmm I think you just need to reset the comp so it gets a new reading. Before or if you already drilled the hole into the cat make sure the negative connector to the battery is disconnected. Then proceed to do the work, if you already installed this and the engine check light is on all you have to do is reset the comp and it should go away. I think its just disconnecting the negative battery cable for a couple secs then putting it back on, I am not complete sure though. Whenever I install new hardware I always have the neg battery cable disconnect. In the past when I didn't know about this, everytime I would install hardware that required sensors my check light would come on. Anyway give that a go and see if it rids the check light. I think I will. BTW you will lose all your radio station presets :P