I know but I would like a way so I don't have too. I want to remove some mods because of lag (also because I want to install different mods ) but I can't because of this. I also can't copy the part of the world I want, then put it into another because of some of the mods I use. MCEdit removes some of Powercraft's blocks and changes Secret Rooms Mod to different blocks (like one-way glass to cake). I noticed forge for a split second will give a choice to continue or not then proceeds to crash. This did work one time back in 1.4.5 when I tried Mysticraft but didn't like it.