3.3.4
Front cross member and/or front or rear sub-frame
Front and rear sub-frames and cross members must be stock and
available on the exact model that is competing in Formula Drift.
The subframe must also be mounted in the exact stock location without being moved in any plane.
Front subframes may only be modified to directly allow for oilpan /
starter clearance and steering rack relocation. The front
subframe must retain intact on at least one major member on one face
that spans the entire width of the subframe, thereby keeping
the original dimensions of the subframe intact. Any other
modifications, cutting,
welding, strengthening, etc is not allowed.
2010-XDC-Rulebook v1.1r.pdf
Any kit that does not modify the stock motor mount locations on
subframe, space there subframe down for trans tunnel clearance,
change pickup points on subframe, or strengthen the
subframe in any way is an illegal kit. You can actually notch
it for oil pan clearance like it states in the rulebook.