Sam Macbeth took five wickets while James Smallwoods scored an unbeaten 76 as the NW Under 17's beat the NCU at Beechgrove to claim the mini-tournament title.
The hosts had beaten Leinster by 13 runs in a game reduced to 20 overs on Monday, while the Dubliners had beaten NCU by 96 runs on Tuesday.
The NCU were bowled out for 145 with Luka Bates top-scoring with 41 and Ali Watt making 28 in their 145 all out - five wickets for St Johnston spinner Sam Macbeth.
Lealand McElwee (23) and James Smallwoods got the reply off to a brisk start with an opening stand of 49 in 5 overs.
Brigade batsman Smallwoods batted superbly making a run-a-ball unbeaten 76 (6 fours, 5 sixes) sealing a six wicket win.