Why 160d6 and not 256d6 (10*1.5^8 dice, rounded to the nearest) or 244d6 (10 * 1.5, riound down, * 1.5, round down,...)? For that matter why not 270d6 (round to nearest each time)?
If you created a spell called Empowered fireball that had the effects of an Empowered fireball (5th level, 15d6...