I am building a 408w for my Mach 1. Its powerband should be from 1500 to 6000, 4 speed topleader, 3.50/3.89 rear. It will occasionally be driver hard, but only for short distances. It has 3 row 24" radiator. What size fan would you give this? The 16" or the twin 14"s? What would be necissary?