Apple is planning to sneak in a modest refresh of its high-end MacBook Pro line later this month according to a new rumor. AppleInsider cites multiple anonymous sources in claiming that Apple’s MacBook Pro line will receive a light bump in late September that delivers marginal speed improvements to the laptops’ Intel Core i-series processors and little else. Intel’s just-announced 2.4GHz, 2.5GHz and 2.7GHz quad-core Core i7 processors are expected to replace the current 2.0GHz, 2.2GHz and 2.3GHz chipsets found in Apple’s current 15 and 17-inch MacBook Pro models, the report says. Apple may also update the current 2.7GHz CPU in the 13-inch MacBook Pro with Intel’s new dual-core 2.8GHz Core i7 chip. If the late-2011 MacBook Pro refresh does occur later this month, AppleInsider says it will take place after September 20th when Apple’s back-to-school promotion is set to end.