Yikes!!! You are really pushing it. The rating on the bulb is typically the measure of power the bulb will use. Not the amount of light produced. The measure of light output is Lumens. A bulbs wattage is a measure of power. It it represented as Watts(P)= Voltage(V) x Current(I) or P=VI. Using the low setting on your original bulbs (55W), your wiring would be handling a current of 55W/12V or 4.6 Amps. Now with the new bulbs (90W), you will be running 90W/12V or 7.5 Amps. Not only is 7.5A a lot but it is 64% higher current draw than your existing bulb. I would not run this amount of current through the stock wiring. You should add relays to handle this amount of current to eliminate a potential wiring meltdown and/or engine fire. For anyone wanting to use a higher wattage bulb, I would say you could get by with a 30-35% increase in current on the factory wiring.

My real recommendation is to replace your bulb with some of the newer bulbs from Phillips or Sylvania Xtravision type bulbs. These will give you 5-15% more light output and stay in the 55-60watt range. Most of the bulbs I have seen out there are junk. I have tried a few of the blue bulbs and they actually have LESS output than standard halogens despite the claims.