The improvement from going to the Euro headlights is dramatic due to the superior reflector shape. Mine, with standard 55/60 H4 bulbs are incredible.
Going to higher wattage bulbs can cause damage to the headlight assemblies and wiring. You will have absolutely fabulous lighting with standard bulbs, save money on their cost and have a long lasting reliable system to boot.
I tweaked my adjustments yesterday morning and was AMAZED at how great they were this morning. Its like having a couple of freight trains running along next to you supplying the light.
Have a great day,