If you only do one ak47 mod do this - Meprolight Tru-Dot Night Sights for AK47 Rifles

This sight set really improves the horrible sights on any stock AK47. Sight picture is easier to acquire in any light conditions. Being able to adjust the rear sight for windage makes it much easier to sight your rifle in and prevents having to crank your front sight post all the way over to the left and or right. I have installed this sight system on over a dozen friends as well as all my personal AK's. If you only invest in one upgrade for your AK do this one!