250-500cc Wr300 power valve setting

Hi fellas.. I have just put a fresh top end in my 2011 wr300. Have read a little about setting the powervalve at 50. 5mm as opposed to 48mm recommended in the manual.. Has anyone else made this adjustment and is it valid for giving a bit more bottom end ? Do you lose up top? And does it cause any problems ie overheating or plug fouling etc.. There is a bit of a thread on here already i know but most of the bikes were pre 2011 models.. Any help would be great b4 i fire the bike up