There are several things you can do to help brighten up your pickups if you are getting a muddy tone. First, try adjusting the height of the pickups by adjusting the screws. If that doesn’t work, try changing your Potentiometer value, if using 250K try 500K. Lastly if that still doesn’t work, try connecting a .047 capacitor in series with the hot output line of your pickup. The capacitor acts as a filter to remove excessive low-end. If that’s still not enough you can to a lower value such as .022μ.