Vehicle catalyst exhaust system for an internal-combustion engine

An internal-combustion engine is provided with an exhaust pipe and an exhaust gas catalyst which can be preheated by a burner. Fuel is fed to this burner from a fuel tank by way of a fuel pump. The pressure of approximately 3 bar existing in a first fuel pipe is increased by an output amplifier to approximately 10 bar. The output amplifier comprises a receiving housing and a guide housing, which is arranged therein as well as a differential piston unit comprising a large piston and a small piston. The differential piston unit has a passage bore, through which the fuel flowing into the pressure space of the receiving housing arrives in the high-pressure space of the guide housing. In the event of displacement of the differential piston, which is acted upon by the pressure medium, in one direction, the fuel present in the high-pressure chamber arrives at 10 bar in the second fuel pipe and from there in the burner.