ArtPB: As an engineer, you are certainly comfortable with some electrical concepts. Volts X amps=watts;A watt is a watt An output of 50 watts is what it is. You can not have an output of 60 or 70 watts out of a 50watts light bulb. You can play with the color of light and other variables but the output will always be 50 watts.
The only way to increase the output is to play with voltage and/or amps.
Saying a 50watts light has 30 or 40% more light than an other light is like saying ''my pound is heavier than yours''