To close this mystery: Any website offering a direct ISO download of "FM4 PSP Exclusive" is either serving malware, ads, or a renamed ROM of a different game.
What makes this version exclusive in design is how it handled the career mode. Unlike the sprawling, somewhat overwhelming menus of console racers, the PSP version streamlined the experience into an event-based structure that was perfect for short bursts of play. It respected the handheld format without sacrificing the depth that simulation fans craved. forza motorsport 4 psp iso exclusive