X: Exene Cervenka, Billy Zoom, Jon Doe, and D.J. Bonebrake, pictured sometime well in advance of their current 31st anniversary tour.

As unabashedly retro, amphetamine-spiked rocksoulpunkabilly two-fers go, you’d be hard-pressed to do better than pioneering Los Angeles punkers X, with garage-rock archeologists the Detroit Cobras on the undercard. Billed as X’s 31st anniversary tour, (though their recorded career began with 1980’s Los Angeles) this greasy double bill pulled into the 9:30 Club Wednesday night for two-and-a-half hours of rocket-fueled Motor City soul and punk.

While X were — are — relentless in their speed and aggression, they’re Clash-type punks as opposed to Sex Pistols punks; the kind that could actually play, and that had more than a half-hour’s worth of memorable songs in them. Their first four albums, from Los Angeles up through 1983’s More Fun in the New World, betray nary a flabby note. Listening to them now, it’s easy to hear signs of the genre sidetrips the band would take later, collectively, as solo artists, and in their roots-music alter ego as The Knitters. Much later, someone would think of a name for what X were doing: cowpunk.