Grandaddy have unveiled details of a new anniversary boxset to celebrate 20 years of their breakthrough album, ‘Sumday’.The anniversary release, called ‘Sumday Twunny’ is a limited edition four LP boxset that will be released on September 1 via Dangerbird. It features a remastered version of the original album in addition to the four-track demos and a set of rarities and B-sides.The entire Sumday: The Cassette Demos collection is available to stream here now and you can pre-order the anniversary set here.In a statement about the anniversary collection, Grandaddy’s Jason Lytle said: “After many years of hammering away at writing and recording as Grandaddy, Sumday seems to be the centre of it and where it all peaked.