depending on the power available, the obvious is a modified car fog light, with the metal beam cutoff strip prised out ( better spread light pattern than a spot light. easy to fit 30w/55w/100w bulbs.
there are a huge number of high power LEDS, running upto 20w now, a bit of ingenuity could have these on the front of the bike. more expense but well worth it. maybe put one in another headlamp/spotlight unit.
the dinky little reflectors that are sometimes available are very innefficient, i used 3 on my c90 due to the miniscule generator, but they weren't brilliant (literally) you can see the diecast box that also doubled as the led current driver heatsink. a 3x10w version would be far superior, mine were only 3W each.
The most effective way of turning petrol into noise without the side-effect of horsepower