PM sent. DvrBARS doesn't do any expansion. To get it up to 4TB, see jmbach's thread. http://www.tivocommunity.com/tivo-vb/showthread.php?t=512153 I went a different route on my 748 by putting a factory 758 image on a 2TB drive. I modified the "brev=" value in Block0, put it in the TiVo to update, then imaged it again. After creating another blank 2TB virtual drive I set up a VMWare virtual machine connected to both VHDs and used jmfs to add the second drive. After that I copied both virtual drives to the appropriate locations on a 4TB drive and edited the partition table and MFS superblock.