No. Do not put higher than stock wattage bulbs in the foglights or headlights, for the reasons stated above. Even with an upgraded wiring harness and relays, there is still the possibility of heat damage to the light housings over time.
Besides that, the additional light output may result in a less than optimal beam pattern from the fogs as they aren't designed to handle the extra light.
If what you're after is supplemental lighting for dark roads, buy some auxiliary driving lights and install them. Fog lights are not intended to serve this purpose and are for use in poor weather conditions only, you can't change that by putting brighter bulbs in them.