CEL from a Test Pipe

Hey everyone,
I recently had my Cat go bad so I tossed a LCE test pipe on. My buddy had one laying around from his old truck. Its giving me a code and smells rich and I'm burning a load of gas. One tank lasts about 3 days of driving where it normally lasts 8-9 days. I've heard that URD used to make a 02 simulator but not anymore. I have also heard using a schematic you can wire one yourself.

Does anyone have any advice or experience on this?

If I cant figure it out ill just have to spend a pretty penny on getting it tuned. Its just a daily so I don't really want to take that route.

 

Or you could just replace your cat

 

Yea... I just like how it sounds withount the cat.