The present invention provides a system and method for the application of a functional thread to secure roving or other fibers to a substrate, thereby forming a precursor to a resultant composite component structure having targeted, enhanced structural reinforcement. The functional thread may be comprised of one or more fibrous filaments or have a monofilament structure. The invention encompasses the sewing of this functional thread at varying stitch densities as function of component stress analysis, the mechanical stresses that the component will be subject to when exposed to the forces and loads associated with its intended use, and at least one physical or mechanical property of a functional thread. This variable stitch density serves to provide targeted, localized mechanical enhancement and reinforcement to the resultant composite structure.