Derek Sheils won the Enkalon Trophy for the second time by taking successes in both legs at Bishopscourt on Saturday.
The Dubliner came come ahead of Wilson Craig Honda rider Marshall Neill by just 0.036 seconds in race one, with Crumlin rider Stephen Thompson third.
Portadown man Neill had to settle for third behind Thompson in race two of the traditional Easter short circuit season curtain-raiser.
CD Racing rider Sheils had previously claimed the title in 2004.
The former Irish Superbike champion will make his debut at the Isle of Man TT in June.
Mark Hanna had a 250cc win and Conor Phillips a 600cc victory.