you probably have a 160 degree thermostat if it only gets to 1/4
Go find a 195 thermostat and it will always be at the halfway mark. I have a 95C (~203F) thermostat in mine right now and it stays right around the halfway mark if not a tiny bit over halfway. A small opening about 2 inches high by 5 wide in front of the radiator is plenty to keep the fan from having to kick on at speeds over 35mph.
lower front air dam added to the bumper will make as big an improvement as the grille block if you haven't added anything underbody to smooth the air flow.