Its actually based on band from norway named Dryads(the band had some success with britpop in norway, but as they where about to sign their first record deal, everything crumbled).
The Dryads gang moved in to another house before the house in the movie. In that house 4 to 6 persons lived. It was not a big house, so when it was time to set up a rehearsal room, a wall had to come down. Without thinking twice about it, or asking for permission from the owners, 20 minutes later and the wall was gone. Now there were space for the drum kit.
In real life the character "Henriette", is a man named Henrik. The creator of the band, and the alpha male in "the gang". In real life, there was no girls in the band or the gang. The band was created after the creation of the gang, 5 pals that were wearing Seventies clothing, a year before it actually in the fashion world, became the fashion of the time. Henrik moved to Oslo because of his music. When Henrik moved to Oslo, the band was dead. But there were something special that came out of all this, The gang without Henrik didn't fall apart, they are still together as a gang of friends, after 23 years, "Haakon Skarpeid who played Bass, Ronny Tønnesland was Manager and everything else that was needed, Christian Høivold played syn-th and Johnny Frivold supported the band any way he could.")