FPGA utilization augmentation in a System Generator core when updating from ISE 13.2 to ISE 14.7
Examining the resulting core with PlanAhead I have discovered that synthesis report files generated by XST synthesizer of 13.2 and 14.4 versions provide erroneous occupancy values.

This bug is resolved in 14.7 version and the real occupancy value is 36%. In fact, always have been 36%.

Jonathan, thank you for the advice of using PlanAhead!!

Best regards