It's very simple to put a 4TB (up to 8TB) drive in your Tivo Bolt. If not using a new Tivo, be aware you will lose all your recordings, have to run setup again, and probably have to re-pair your cableCARD. I did. The upside is you'll go from about 75 hours of recording capacity to about 640 hours.
Do this at your own risk, I'm pretty sure it voids the warranty. Not included are some common-sense things like being grounded ( I'm in Florida, static electricity wasn't an issue when shooting this), shutting down PC before attaching HDD, and not letting Windows reformat or partition the 4TB HDD when it recognizes it. If you are electronically challenged, get a niece, nephew, or grandchild to do it for you.
Tivo Bolt, renewed 500GB, holiday sale, $99.99
https://www.tivo.com/2016Holiday#/2016Holiday
4TB drive, $109.99 Black Friday Sale:
https://www.amazon.com/gp/product/B0196J3UZ2/ref=oh_aui_detailpage_o01_s00?ie=UTF8&psc=1
Software acquired here:
http://www.tivocommunity.com/community/index.php?threads/mfs-reformatter-mfsr.528428/#post-10501034
Instructions I followed:
http://www.rosswalker.co.uk/tivo_upgrade/#BOLT
