You would have to edit the global.php file to change this
FIND:
Code:
if (($vbphrase['pmpercent_nav_compiled'] = number_format($vbulletin->userinfo['pmtotal'] / $vbulletin->userinfo['permissions']['pmquota'] * 100, 0)) >= 90)
CHANGE TO
Code:
if (($vbphrase['pmpercent_nav_compiled'] = number_format($vbulletin->userinfo['pmtotal'] / $vbulletin->userinfo['permissions']['pmquota'] * 100, 0)) >= 0)
As always I never recomend editing stock vb files.