The wickets continued to fall at a steady rate and only two Sri Lankan batsman posted double-figure totals.
The Black Caps needed only half of the available overs in their reply to chase down the total on a record-breaking day.
Guptill, who scored 58 in the first T20 and starred with 331 runs in the one-day international series, continued his fine form and scored the fastest-ever T20 half-century by a New Zealander in just 19 balls.
Astonishingly, it was a record that would last less than an hour as Munro, upon Guptill's dismissal for 63, came in and smashed an unbeaten 50 off just 14 balls - the second-fastest 50 ever in T20 internationals behind India's Yuvraj Singh (12 balls).
By taking only 10 overs to reach 143, New Zealand smashed the previous best for a chase of above 120, which was set by South Africa when they managed 130 in 11.3 overs.