resizing isn't all that hard. if you select all the vertices of every MA on the part, you get that wheely thing with the red, blue, and green circles with the arrows and squares within it. if you click and drag the little squares and the circles, you can stretch and rotate the top until it fits as best as possible without any skin phasing through. just a warning, make sure you select any and all bones/physics/joints in the top (in this case the stuff on the collar and zipper) along with the vertices. otherwise, they wont be properly aligned with the part and that will probably cause some problems. xD another thing to look out for is sometimes the rigging jobs in some parts disagree with the model type ESPECIALLY if the part is FAR from being suitable for your model's type. i know because i have a TDA model of an OC wearing a shirt meant for the Animasa type or whatever the default mmd model type is called. xwx anyway, i hope all went well with you and your model~ ^^