With the Hunters that have a B & R rig (No Backstay, Swept back spreaders) the standard jib is a 105 to 110%. You can go larger but that is what it is designed for. The main in that rig provides most of the power. Enough so that in 15 knots of wind a reef in the main is appropriate. You don't need a larger jib like the masthead rigs of the 70's. You'll pass them while they are cranking in those enormous 150's and getting tired.
However, the main should be well shaped. Blown out will cause the boat to sail poorly - excessive heel, too much rudder, won't point, slow! Put the first money into the main, in my opinion.