To echo what Mr. Clean said, if he is in LE, most department policies explicitly forbid modifying triggers on duty weapons, if it's his personal weapon that he uses on duty the policy could be different, but I still wouldn't recommend changing striker springs on a duty gun. When you start f'ing with striker springs, you create a large opportunity for light strikes in the glock platform. A fluff and buff on the internals and a minus connector is probably all it needs, and IMO if it's a newer gen 4 with the "dot" connector, a fluff and buff is all it needs. The minus connector in my experience is mushier than the dot. Take whatever money he intended to invest in gucci glock parts and spend it on ammo and training. It will pay larger dividends.