Complex sentence: As a result, Paul Doucette took over rhythm guitar, and the band reunited and released a compilation album, "Exile on Mainstream", in 2007, which was certified Gold in the United States.
Split into simpler sentences: As a result, Paul Doucette took over rhythm guitar after the band reunited in 2007. They released a compilation album, "Exile on Mainstream", which was certified Gold in the United States.