Pico are hand built sound systems erected in chiva, or local bus/truch transport, in Cartegena, Colombia. The large speakers and boom boxes are tricked out like juke boxes, and the entire brightly painted chiva becomes a music hall. I could only find a few photos (email me if you find more). Here is an abstract of a scholarly examination of the tech culture.

Sound Systems, World Beat and Diasporan Identity in Cartagena, Colombia
Deborah Pacini Hernandez in Diaspora: Volume 5, Number 3, Winter 1996

Afro-Caribbean music plays a large role iin Cartagena, Colombia, a city with a large population of African origin. Hernandez details the ways in which the Colombian recording and broadcast industries resisted the dissemination of such music, and discusses the material practices centered around picos, locally constructed sound-systems, through which African-Colombians acquired, reproduced, disseminated, and transformed recorded diasporan musics. She notes that the black Cartageneros’ production of such music systems preceded the appearance of world beat in northern contexts by almost a decade, and traces their acknowledgment of and participation in a diasporic Afro-Caribbean identity based on musica africana.