A rally car engine is basically the same engine you can find in a production model version of the car being raced, with some minor differences. The biggest is that these engines produce much larger quantities of power. This is accomplished by using much higher boost pressures, larger pistons and valves, and other minor modifications that create more horsepower. Rally car engines are also built with heavier duty parts in order to keep from breaking under the high stresses during a rally race. In order to control the amount of horsepower produced by these engines, the sanctioning body mandates a restrictor plate of 34 mm be installed before the turbocharger inlet.