Watch the Filtration Blues online guitar lesson by Stephen Bennett from Fingerstyle Finesse
The first video lesson finshes up the breakdown for Burnside. The second video kicks off the Filtration Blues series.
Filtration Blues is a bluesy tune, although certainly not a typical blues form. It doesn't ever get played the same way twice. The basic structure of it remains constant, but the melody (at least in the verse) is wide open for improvising. You are only constrained by the need to maintain the bass line. And good taste, of course. And your abilities, but hey, that's not my problem.
Seriously, do try your hand at improvising a bit within the song structure and see what happens. What's the worst that can happen? Aside from your spouse leaving you and your dog starting to growl at you because you haven't been practicing hard enough...