An apparatus and method for achieving increased NOx removal efficiency from an emissions control portion of a fossil fuel fired boiler while controlling ammonia slip provides excess levels of ammonia above those levels conventionally employed in SCR and/or SNCR applications. The apparatus and methods comprise, in part, use of a NOx reduction system comprising at least one selective catalytic reduction system which receives ammonia in higher amounts than conventional practice from an upstream ammonia injection point, and an ammonia reduction system positioned downstream of one or more ammonia injection points and the NOx reduction system. The excess ammonia achieves increased NOx removal, while the ammonia reduction system contains at least one ammonia destruction catalyst which permits the NOx reduction system to be operated at an increased NOx removal efficiency without a corresponding increase in ammonia slip.