The "nose" of the ZTrix.com IMSA kit is designed specifically to mate up to the IMSA front fenders and it flares out to match the width of the wheel wells. It incorporates a full-height airdam that can be trimmed to adjust for ground clearance and/or use a rubber or plastic skirt (not included).
IMSA nose mounting is via factory fender mounting locations and through-bolts attaching to the fenders at the sides. However, many customers have fabricated brackets with telescoping tubing or brackets to bolt-on to bumper mount locations...this allows for quick removal of the nose to facilitate trailer loading, easier shop service via floor jack, and/or quick change for racing use.
FYI, the IMSA nose is such a big piece that it has to ship in its own box, separate from the fenders and quarter panels. So, I have to charge for two custom boxes. But the good news is that shipping two boxes of this size to the same address doesn't change the freight cost much.