I don't know what mag's your reading,but every one I've read show them very close with the trx stronger on the bottom and the yamaha stronger on top....

 

Obviously the milder 450r is gonna have more low end than the YFZ. The YFZ is tuned for high rpm power. All other dyno graphs show more than 1 HP or so difference at peak power. Here is the mag shootout results:
stock <FONT style="BACKGROUND-COLOR: yellow">450r</FONT> honda- 37hp at 7300 rpm
stock 450 YFZ yamaha- 39.3 at 8050
yamaha with gyrt slip on, air box mods- 44.6 at 8200
honda <FONT style="BACKGROUND-COLOR: yellow">450r</FONT> with white bros pipe, air box mods 40.0 hp at 7200