This is basically the first thing I do to every Glock i acquire. The "humps" do not fit my fingers at all, and must go. The top hump crowds my middle finger, and the second hump hits dead square in the middle of my ring finger every time. I just take the angle grinder to it until the front strap is straight like a Gen2. On the large frames (20, 21) I take all the checkering off the front strap, down to smooth plastic, and apply 3M tread tape to the front strap. This reduces te overall size of the grip a little, and the tape gives superior grip.
Happy shooting, Tom