Since nobody answered ushahid's question...
This building has 3m tall floors, so 157m would have netted you 3 additional floors over the present 148m height.
At an average residential tower floorplate of 675sqm, that would be an additional 2,025sqm, totaling 27,116.5sqm for the building. With a site area of 782sqm, this would give an FSI of 34.67. Compared to the present FSI of 32.09.
FSI is a good mechanism for City Planners to figure out how to feel about a development application, especially when comparing two neighbouring sites with differing lot sizes, but beyond this simply bureaucratic "efficiency", I wonder what value we gain as a city in using FSI as a metric for determining the right mix and density of housing and commercial activity. Would three extra floors make this development right in the thick of the downtown core "bad planning" instead of "good planning"? In an area like the downtown core, shouldn't that be determined by the market and the development proponent?