At Miller Performance, we carry the AEM UEGO wideband air fuel ratio (AFR) gauge. For basic AFR monitoring, we have always used AEM. The UEGO wideband kit brings you piece of mind knowing what your air fuel ratio is at all times. This helps protect your investment and allows for easier diagnostics if something goes wrong on your engine. New to our AFR gauge line up is the Miller VCLC system. This special gauge interacts with the WAR Chip and keeps your turbo M20 or turbo M30 in constant closed loop operation with a variable target based on boost! That means instead of going open loop and running off a fixed fuel value, the ECU can adapt in and out of boost to maintain the ideal air fuel ratio for the given condition!