Basic wind tunnel boundary correction schemes for closed jet test section wind tunnels are not generally applicable for complex flows about bluff bodies whose frontal area exceeds approximately 7.5% of the cross-sectional area of the test section. When model sizes are greater than 7.5%, advanced boundary correction schemes capable of resolving wind tunnel boundary effects are required. To evaluate the utility of an advanced boundary correction scheme, the Wall Signature Method was employed to study the drag produced by two dimensional flat plates of various sizes from 2.5% to 33% in a closed test section wind tunnel. Experimental and computational results of drag coefficient, uncorrected for blockage, as a function of blockage ratio already exist for this model problem. Additional results from a viscous computation, including tunnel wall pressures and flow streamlines, are included. Corrections were made to the drag coefficients using blockage correction factors determined using the Wall Signature Method. The blockage corrected drag coefficients were compared to the accepted freestream value. The validity of the supposition that pressure correction schemes work acceptably well for problems where the wake bubble may be distorted but the separation point remains fixed is studied.