After buying a complete system from Nitrous Express, I am currently installing and wiring my FED. I purchased a maximizer 5 progressive controller unit with the intention of hooking up an AFR sensor to it to safeguard my engine. It has become apparent that I do not fully understand the components of such a system. I went to buy a sensor then found out that I need to purchase a complete module which then plugs into something else. After totaling up the cost I hit at about $800 and stopped before I purchased to get some advice. What do I really need to have a functioning sensor that I can hook up to the Lambda wire of my max 5. The company has suggested I stick with a system from AEM or Innovative. If I can't figure this out the only other option is a $3 plug for the bung....which does not look too bad right now.