Thrash-metal quartet Black Fast's priority is self-improvement, not self-promotion. The obsessively tight band has only emerged from its practice space a handful of times since its debut last summer. Most of its fans witnessed the band by accidentally catching opening sets for Liturgy, Cross Examination or the Gorge. Its name is virtually unGoogleable. Its entire Internet presence is an ill-run MySpace page and live YouTube bootlegs. Its handmade CDR-EP, in '80s LA tape-trading fashion, must be obtained from a band member. Black Fast's take on the genre is authentic but not elitist, referencing Iron Maiden's endless sweeps, Megadeth's hook-laden riffs and Mastodon's stoner-friendly structures. We'd be hard pressed to find a more purified source of metal in St. Louis, even if we melted down the Arch and sold it for scrap.