Whilst I do run a pair of Vision X Solstice LED spots, by far the best bang-for-buck modification to the headlights on the Z is to wire them up so dip beam stays on when main is selected. A mod well worth doing.
It can be done for the price of a Scotchlok. Simply locate the rubber boot on the right hand side that protects the headlamp loom connectors, just above the radiator, and bridge the blue/black wire and the green wire. It is possible to do with the tank in situ if you've got small hands and patience, but is far easier with it removed.
These two wires can also be soldered together in the switch as an alternative.
One cautionary note though: This mod is only recommended for a maximum of 55W bulbs in both main and dip. It is inadvisable to use 100W bulbs as the all the current is carried in the green wire for both lamps. The cross-sectional area of the the headlamp wiring is gives a rating of 16A (even though the fuse is 20A!), so the theoretical safe maximum is 192W combined (although it will be slightly more if the engine is running and at peak alternator output). However, bear in mind 192W is using up
ALL the spare capacity of the alternator