Fans of the late Frank Zappa may be interested in two shows by Detroit’s only Zappa/Mothers tribute band, Ugy Radio Rebellion. The group – which is usually a trio – is touring this summer with Ike Willis, who spent 17 years as a guitarist and vocalist with Zappa. He’s probably best known as the voice of Joe on Zappa’s Joe’s Garage LP. The group – with Willis on hand – will be performing tonight (June 5th) at Park Bar Downtown (2040 Park Ave; one block west of Ford Field; 313-962-2933), and then again on Friday, June 13th at the Cadieux Café (4300 Cadieux Rd.; between Mack and Warren; 313-882 8560). Strictly commercial? Or no commercial potential? You be the judge