I've found the statement "Note: In case of deviation from the chart reference conditions (QNH, air conditioning…), corrections have to be applied to the flexible temperature" in Airbus Getting Grips With Aircraft Performance, under page 7.1.3. Flexible Temperature Determination.
Like Cough's said "required thrust stays the same, it can just be achieved at a higher flex temp with the packs off" is the reason for EGT Reduction. Cheers all, thanks for the insight.
Bolubo: Tell me we're in the same island!
