Thursday at the Cuthbert Michael Franti may be the main attraction, but there’s no reason to brush opener Trombone Shorty aside. The six-man group’s sound is fiery hot, swingin’, groovin’, funkadelic and always tight. It’s really tough to make brass the centerpiece of a sound, with guitar basically becoming part of the rhythm section and wicked horn chops furiously taking over the lead. Trombone Shorty pulls this off with might and intensity that’s impossible to ignore. Get to Cuthbert Amphitheater early and set your toes tapping, your head lulling and your heart aflame; you won’t regret it. Trombone Shorty opens for Michael Franti & Spearhead 6:30 pm Thursday, Aug. 23, at Cuthbert Amphitheater; $40 adv., $45 D.O.S.