[Zantox]

PHP Code:

if ($vbulletin->GPC['year'] < 1970 OR (mktime(0, 0, 0, $vbulletin->GPC['month'], $vbulletin->GPC['day'], $vbulletin->GPC['year']) <= mktime(0, 0, 0, $current['month'], $current['day'], $current['year'] - 13))) 


Find this in register.php and change the 13 to what you wish the age to be.
This will change the COPA age requirement, you will need to enable that in registration options.