Standalone ECUs can be pricier and require more modifications than factory ones

and racing thermostat

They are designed to replace BMW part #11241247175

1982-1994     E30     320i

BMW has released these engines in several revisions

Mishimoto Thermostat, BMW M52TU / M54 430i Standalone ECUs can be pricierMishimoto has developed a direct fit replacement thermostat for the BMW M52, M54, and M56 engines. This Mishimoto thermostat is the ideal replacement for your failed stock thermostat. The Mishimoto thermostat comes pre installed in a durable OEM quality housing and fits many BMWs including E46, E39, and E85 chassis. Like all Mishimoto cooling products, this BMW M52, M54, and M56 thermostat is backed by the Mishimoto Lifetime Warranty. Applications: