Outlook 2010 Create OST size limit

Regedit:
HKEY_CURRENT_USER\Software\Microsoft\Office\14.0\Outlook\OST

Modify MaxFileSize, WarnFileSize, MaxLargeFileSize, WarnLargeFileSize.

Also works for 2003 and 2007:
Outlook 2003 » HKEY_CURRENT_USER\Software\Microsoft\Office\11.0\Outlook\OST
Outlook 2007 » HKEY_CURRENT_USER\Software\Microsoft\Office\12.0\Outlook\OST

Source: ostfile