I have an older Heil NUGE 125A501 furnace. I'm trying to find out if the blower has multiple settings I can change for higher cfm.

The blower normally has three speeds if it supports air conditioning. The blower is set for high speed on AC, but sometimes they are set to medium. If that is the case switch the medium speed for high. Usually, medium speed is the blue wire and high is black. The speed for the AC is plugged onto the fan relay. Never short out two fan speeds as it will burn up motor instantly.