Increasing Zombie Detection Range

[Micro230]

//ZOMBIES THINK
function GM:Think()
	for _, ply in pairs (player.GetAll()) do
		local plypos = ply:GetPos()
		
		local Zombies = ents.FindByClass("npc_zombie")

		for _, ZombieMind in pairs( Zombies ) do
				
			if ZombieMind:IsCurrentSchedule ( SCHED_IDLE_STAND ) or ZombieMind:IsCurrentSchedule ( SCHED_COMBAT_STAND ) or ZombieMind:IsCurrentSchedule ( SCHED_ALERT_STAND ) then
				if (plypos:Distance(ZombieMind:GetPos()) < 100000) then
					ZombieMind:SetEnemy( ply )
					ZombieMind:SetLastPosition( plypos )
					ZombieMind:UpdateEnemyMemory( ply, plypos )
					ZombieMind:SetSchedule( SCHED_CHASE_ENEMY )
					ZombieMind:NavSetGoalTarget( ply, plypos )
					ZombieMind:Activate()
				end
			end				
		end
	end
end

I am trying to increase the zombie detection range but it doesn't look like it is working. Without creating a new zombie is there a way to increase it?

If I do have to create a new zombie, is there a way I can copy the default HL2 zombie and modify it? Thanks for any help! :)