Goals from Liam Moran, Leon Squire and Bradley Easey secured a brilliant away win for the young Pilgrims in their latest Football Conference Youth Alliance fixture.
United twice trailed, but hit back within a minute each time through Moran and Squire, with Easey sealing their second win in three with a brilliant goal on 75 minutes.
Boston (4-3-3): Jamie Bradley; Daniel Worthington, Josh Spencer, Joe Cain, Corey Newman; Aaron Eyett, Jacob Pease, Bradley Easey; Louis Saebe (Steven Dovey 60), Liam Moran (Karolis Andriulionis 65), Leon Squire.