yes, higher wattage bulbs can fry your wires. They were not designed to carry the higher current.

Think about running your stove or dryer on 14 ga wiring.

Not pretty...


Not to mention illegal... but that is a different argument.

 

I've fried the wires of 9007s before running high wattage bulbs. You can get the upgrade harness to draw the power straight off the battery to eliminate this but it won't work well with day time running lights. Basically, rather than the day time lights running low power, if you have the upgraded harness, they will run full power all the time. You'll go through bulbs like water.