Scheme of metal removal from a piston to adjust its mass
The arrows indicate the places where metal can be removed.
The mass of pistons in one engine must not differ from each other by more than ±2.5 g.
If there is no set of pistons of the same weight group, you can remove some of the metal at the base of the piston pin bosses. The location of the metal removal is indicated by arrows in the figure.
The material is posted on the website (VazBook)
The metal removal, however, should not exceed 4.5 mm in depth relative to the nominal piston height (59.40 mm), and in width it is limited to a diameter of 70.5 mm.