No, the aluminum trigger does not change the actual trigger pull in terms of weight. What it does do is to reduce the pre-travel and after-travel of the trigger. Since it both reduces pre-travel (that is, the distance the trigger moves before it starts to actuate the hammer) and has less curve than the factory trigger, it provides more room in the trigger guard for your finger, eliminating trigger guard "slap" during recoil. It also is designed so that trigger "pinch" (something many folks experience with the factory trigger) is eliminated. Also, the aluminum trigger is wider than the factory trigger. This reduces the "perceived" effort needed to pull the trigger, so it feels lighter even though actual pull weight is the same (which is a good thing, since actually reducing the trigger pull weight in a self defense pistol can can adverse legal implications).
Jim R