Robin Hanson wrote about similar experiments in 2010: http://www.overcomingbias.com/2010/07/looking-too-good.html

As others here have suggested (e.g. jpfed, Tade0), it seems that extreme generosity can be regarded as establishing an undesirable behavior standard. The post suggests a workaround, if your productivity/generosity greatly exceeds others: under-report your output and give credit to others.