How much could new boilers improve Incomparable?

How much could 1930s boilers improve Incomparable over her original machinery?

A major improvement is expected, although no numerical gain is calculated. The original proposal used Yarrow boilers for 180,000 shaft horsepower.

A major machinery improvement is expected between the original proposal and a refit in the 1930s. The original Yarrow-boiler machinery was intended to deliver 180,000 shaft horsepower. No numerical gain is calculated, and the discussion distinguishes between early- and late-1930s refits. The long hull would also give a choice of 4-inch, 4.5-inch, or 5.25-inch dual-purpose secondary mounts.