Here is the full list of all 19 Thumper achievements.
Get S Rank on all levels
Get S Rank on Level 9
Get S Rank on Level 8
Get S Rank on Level 7
Get S Rank on Level 6
Get S Rank on Level 5
Get S Rank on Level 4
Complete all levels
Complete Level 8
Complete Level 7
Complete Level 6
Complete Level 5
Complete Level 4
Get S Rank on Level 3
Complete Level 3
Get S Rank on Level 2
Complete Level 2
Get S Rank on Level 1
Complete Level 1