Boeing (NYSE: BA) is actively considering upgraded versions of its largest and smallest 737 Max jets to ward off competition from above and below. In a Flight Global story Monday, 737 Vice President and General Manager Keith Leverkuhn said that while augmentations are on the table, no decisions have been made. “The jury is still out,” Leverkuhn said. On the bottom end, the Boeing-Airbus hammerlock on the single aisle segment was breached last week when Bombardier won an order for 75 CS100…