As Ian said, every car will be a bit different.
At a guess, I would say that it was more about total flow through the intake, engine and exhaust rather than power.
Nurrish- I can't remember what your inlet / exhaust set up was. Maybe with the SSV, decat and true dual exhaust mine is flowing more than yours was? I remember you had the 2.87 pulley so your high power would have been through the increased boost.
Ian had a Cosworth plenum so maybe the improved plenums are the reason for the extra flow?
Mark said my MAF topped out at 5.04v at 6000 rpm so power and torque took a plunge from there.