I made i video based on the tips of Sir Loinsteak, this glith still works!
Just made a save point before you made any achievement, make that achievement and close the game going back to your dashboard, start the game again, Shadow Warrior make auto load on your save game, just make the achievement again and close the game, this count 2% on Achievement Hunter 150G Achievement.
My tip is, make this boost before you buy your 5 weapon upgrade and your 10 Skill ability, made a save with 4 weapon upgrades and 9 skills, your boost gonna be more fast than my.
Here my video: