Thanks - I meant to update my comment after I went and looked up xz, I've used 7...

EwanToo on March 1, 2013 | parent | context | favorite | on: Compress data more densely with Zopfli

Thanks - I meant to update my comment after I went and looked up xz, I've used 7zip and LZMA before, but I've never directly come across a .xz file, odd!