First of all, don't think is street legal. Secondly, you double the wattage which means you double the current. Also, is your lens going to be able to handle the extra heat dissipated by the doubled wattage bulb? The insulation of the wiring in a 20-year old car had been aging. In general, its not a good idea and don't do it unless you know wwhat you are doing. My $0.2 opinion.