What are these four tubes for in the intake for an Extra 300?
Those are the impact tubes for the fuel metering for the RSA-type fuel injection system:



Above is the face of the fuel servo. If you had more light you would have also seen the throttle valve as shown above. When the throttle opens, air rushes in, and the higher pressure in the impact tubes would deliver more fuel. See schematic and description below:


... As a result, the diaphragm moves to the left, opening the ball valve. Contributing to this force is the impact pressure that is picked up by the impact tubes. [Figure 2-32] This pressure differential is referred to as the &quot;air metering force.&quot; This force is accomplished by channeling the impact and venturi suction pressures to opposite sides of a diaphragm.


Source: FAA-H-8083-32A. Aviation Maintenance Technician Handbook-Powerplant Volume 1.