The system consists of an extractable mobile structure, equipped with motorized adjustment systems which are inserted underneath the forming line belt immediately below the regulation scalper. Each actuator is able to differentiate the height of the mat below the scalper to obtain an even and uniform distribution of the transversal weight of the mat and consequently of the end board produced as well. The actuators have a maximum run of 100 mm. Each regulator is equipped with an absolute position transducer, so that the position of each regulator is known at any time throughout production. This has the advantage that the regulators may be placed in the previously stored ideal position at each production changeover. With an appropriate processing of the signal received, it is also possible to obtain the real time transversal density profile of the mat, which may be reproduced with current graphic technology (3D, colour) for a clear view of the mat and to highlight any forming defects which may be present.