If the 'pop' typically occurs once or maybe twice during the motion of going up (I never noticed it going down), it 'might' be due to lack of lubrication of the plastic spindle where the spool on the window glass holder plate attaches to the regulator mechanism. The white plastic spool on the glass holder is supposed to move smoothly horizontally on the spindle as the window goes up and down. I think it accommodates the curvature in the door. With lack of lubrication the spool sticks on the spindle. When you raise the window it does not move until the horizontal force on the spool gets quite high and then it snaps across the shaft with a fairly loud pop. I discovered this after I installed my Hugo kit, replaced the glides, cleaned the tracks ....; but, failed to lubricate the spindle. I developed the pop almost immediately, I think because the window was moving much faster than it did before. Taking the door apart again and applying some urea grease to the spindle fixed the problem. I think in the Wiki there is a copy of a Honda Technical Service Bulletin describing the problem and the fix (TSB-93-004).