Big holes in the firewall are clearly not consistent with accurate replication of a 1:1 vehicle that has no big holes or slots. Even in "Out of the Box" classes, big gaps or holes or slots in the firewall or anywhere else are bad, bad, bad.
Just helped judge an IPMS model car contest yesterday and the list of craftsmanship errors that caused models to beat themselves out of contention were pronounced, and quite typical:
1) Visible trademark and/or parts number engraving, ejector pin marks, mold parting lines/molding seams, sprue nubs or attachment points.
2) Glue goobers or smears.
3) Poor paint finishes: orange peel, grit under paint, bubbled clear coats, dull color coats, cutting or sanding gouges visible under paint, overspray, bleeding or fuzzy paint separation, bare plastic showing (especially undersides of interiors or fenders where not concealed by the chassis ~ think driveshaft tunnel).
4) Wheels/tires attached at cockeyed angles (not aligned), all tires not touching table, mold lines down the centers of tires, wheels/tires too large to rotate or turn (fronts) within fenders.
5) Poor fitment of windows and windshields, including big gaps between glass and body.
6) Sloppy decaling (silvering, decals spanning panel lines, chrome trim, or door openings that were not trimmed to accommodate 1:1 operation of doors, trunks, etc.).
It was amazing how many winners (and their ranking) were decided by basic craftsmanship issues, not expert execution of advanced techniques! Many models with killer-gotcha paintjobs were beaten out because the models had major craftsmanship faux pas while the more "ordinary" paintjobs were flawlessly executed on models exhibiting clean, careful craftsmanship.
Not once did photoetch or exotic aftermarket stuff boost a model over clean building.
Food for thought.