Put this on my FL5 as I plan to track it. First time out it worked fine, but I did get a CEL (ECU detects the thermostat opening sooner than normal, so since water temps don't reach a target value before it opens, a code is thrown), which others had warned about. Talked to my tuner and he was able to take care of that so I don't get a CEL from it anymore. Combined this thermostat with a PWR racing radiator and the Acuity reverse flow hoses, and I've had no overheating issues at the track.