Adding a thicker string to the guitar to go even lower down on the musical scale. The gauge is 065 and tuned to #F.
Kim:"I thought I'd try to tune down as low as the 8-strings to see how it is to play like that. I went to the shop to buy strings and I wanted a 066 guitar string, but they didn't have that in stock so I bought a bass-string at gauge 065 instead, and it works fine. The tuning feels really low, I might have to get me some guitar subs for my guitar rack".