The Pilgrims were too strong for the Coasters at the Jakemans Community Stadium, with Owen Sheriff also on target.
It was United's second win from three on the venue's new 3G pitch.
Boston (3-4-2-1): Charlie Wilkinson; Bailey Dilley, Owen Sheriff, Ben Robson; Krisztian Gagyi, Haydn Tear, Joe Melson, Zane Millar; Finlay Armond, Ben Johnson; Sam Harris. Subs (used): Han Stevens, Logan Tate, Jake Henderson; (unused): Taylor Jaine, Oliver Ford (gk).
Referee: Alistair Wilson.