I made my own and they have worked wonderfully for the past month and a half. These are not the plug in type either, the ones that I made go directly in line with the O2 sensor. Let me know if I can be of further assistance.
Once I put my mils on my check engine light still came on, but then I got the diablo tuner and there's an option that lets you just turn the sensors off. Haven't had a prob since