Got a low system performance code for one of my cats. It's pretty much plugged. Killing my gas mileage. The engine is freshly rebuilt. I don't have emissions testing in MI so I don't care about the cats. Pre cat O2s control my air fuel mixture so I'm good to go. Surely someone makes that down pipe for the 4.0 without the cats right? I found one somewhere last fall and now I can't find it again for anything. Thanks ahead of time for any info. I'm not exactly a great pipe bender. I really want to find a pre fab.