As a legal alternative to high Watt bulbs, You can get a H4 60/55w bulb that is supposed to produce the equivalent of 140/130W. PIAA NIGHT TECH

I need new bulbs after one fell apart at silverstone last year, so might try those, or for ultimate power there are these 80/80W equivalent of 150/150W COMPETITION

Lokking at the price of those competition bulbs, the night tech ones look a much better option.