You can tweak the params in the postHDR material.
Taken from the postHDR shader:
Code:
Description for uniform 'hdrParams' values:
a - Exposure (higher values make scene brighter)
b - Brightpass threshold (intensity where blooming begins)
c - BrightPass offset (smaller values produce stronger blooming)
The default tone mapper from the samples is relatively primitive. You can use nicer ones but this requires some serious shader programming skills.
Another general note, no offense at all:

Please keep the size of such "debugging" images as small as possible (shiny screenshots in the showcase can be larger of course). We only have limited disk space on the server.