It only increase ST ranged powers, cone powers (cone+range) and targeted-AoE (the range, not the AoE). So no range increase of PBAoE's (as dreadfull is).
50)Sinergy X/(50)Mika.
(50)MaceX/(50)Encore
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Ok thanks for that 
So yeah, in a nutshell, it doesn't increase the radius of powers, but it's still very useful.
I have a Sonic/EM Blaster that i got to 35 over the Double XP Weekend, and i was wondering if i got Boost Range would it increas the range of Dreadful Wail ??