Blackalicious showed off its linguistic prowess some years back on a single called "Alphabet Aerobics." As for lightning-lipped Los Angeles MC Busdriver -- another denizen of the hip-hop underground -- he's spent the double-aughts pushing his verbal virtuosity past levels that'd wear out manic Celebrity Fit Club trainer Harvey Walden. The son of the guy who wrote the screenplay for the cinematic B-boy classic Krush Groove, Bus, aka Regan Farquhar, began developing his singular, speedy and quite often impenetrable flow at the age of fifteen; he was a regular during open-mike nights at L.A.'s Good Life Cafe, proving ground for the famed Freestyle Fellowship collective, Jurassic 5, the Pharcyde and what would eventually become the Project Blowed crew (Bus is a charter member, along with Aceyalone, who shares the bill this Wednesday). In later years, he became known for rhyming hyper-sonically and hyper-literately about love (more like failed love) and sociopolitics over crafty, super-tweaked IDM, jazz and old-school textures and breaks on a handful of solo and collaborative releases. But Busdriver shifted gears lightly on last year's Fear of a Black Tangent, swapping out some of his usual twisted, observational humor for grim commentary on the tribulations of an underdog, commercially unviable rapper. That might change now that he's signed to Epitaph and working on a new album -- whose material he's likely to unveil at this Boulder show.