This AEM/FAU unit is a faster, more durable sensor. While the Bosch 4.9 LSU has excellent light off and response time, its performance tends to diminish rapidly in high performance racing applications where leaded fuels and rich fuel mixtures are more common, as are violent events like 2-step rev limiters in drag racing, high frequency vibrations, and upper rev limiters in drifting and other forms of motorsports. AEM's goal was to design a sensor capable of surviving for extended periods in these extreme environments, and after five years of development and testing with FAE, the company has validated its new sensor to last longer in harsh environments and have a faster response time than the Bosch 4.9 LSU.