Per the Bosch Automotive Handbook (9th edition 2014) “The required filter fineness is dependent on the fuel-injection system. For systems with manifold injection, the filter element has a mean pore size of approximately 10-microns. Finer filtering is required for gasoline-direct injection. The mean pore width here is in the range of 5-microns”. The vast majority of high performance fuel systems utilize manifold injection and therefore, a 10-micron filter element is appropriate.