The problem with 9004 is that its low-beam is only 45 watts, compared to other types (H4, 9007, etc) that have 55W low-beam. Obviously this makes 9004 weaker than the other bulbs.
For this reason, some people try and swap 9007's into the 9004 socket (to get the 9007's 55W low-beam), often with poor results (they look like they are interchangeable but they are not because high and low beam are switched around).
Those bright xenon 55w=85w blue light specials are scams that actually give you LESS light only add to the confusion.
So what is the solution for a 9004 user?
Wagner BriteLite 9004BL. It is a 9004 bulb with a 55W low-beam (and of course, the standard 65W high beam)
Has anybody tried these?