Not knowing whether or not you have bought and installed any textures for M4 it's hard to say. His free standard resolution nude texture pose is called !All_Natural.pz2 and the one with the boxer briefs on it is called !Body_BoxerBriefs.pz2. There's also a !Head_Bald.pz2 and a !Head_Hair.pz2 in the same folder which should be called  MATerials STD-Res and be under your Michael 4 pose folder.