The weird part is that if I create the boot image as part of the "Create MDT Task Sequence" wizard and then use that boot image to create a boot disk, everything works fine, the boot disk size is about 292MB (with the prestart commands included), but if I build a boot image from "Create Boot Image using MDT" and create a boot disk based on this image the image size is almost 3GB (maybe this is a bug?).
Thanks