FRIDAY 4 PM, 5TH UPDATE WRITETHRU: It’s shaping up as a very strong domestic box office weekend with Summer 2013 continuing to sizzle. My sources say that, based on matinee trends, Universal’s and Illumination Entertainment’s holdover Despicable Me 2 should be #1 again this weekend with high $40sM and only a -51% drop from last weekend. But Pacific Rim (3,275 theaters and 331 IMAX screens) keeps surging and looks right now like mid $40sM. That’s including Thursday late shows and Friday midnights which Warner Bros says the Legendary picture overperformed with $3.6M. I’ve learned the 3D ratio is a strong 52% “and the largest ratio of a wide release for a very long time” according to an exec. And finallySony Pictures/Happy Madison’s Growns-Ups 2 (3,491 theaters)also started with bigger than expected $2.3M late shows even though it’s a PG-13 family, non-fanboy, non-IMAX movie. Now it’s shaping up as low $40sM, which would beat the 2010 first installment’s $40.5M opening weekend. According to the latest Rotten Tomatoes scores, it’s not even a close contest between the mecha anime inspired thriller and the Adam Sandlerensemble sequel: Pacific Rim has 72% positive reviews while Grown-Ups 2 an astoundingly awful 5%. (Ouch!) As of 9:00 AM PT this morning on Fandango, the three top films were selling neck and neck online and through mobile: 31% for Pacific Rim, 30% for Despicable Me 2, and 28% for Grown-Ups 2.