I wound up putting higher wattage bulbs in my Dad's Monte Carlo after we smoked the tail lights. The bulbs were 12 volt, just a little bit brigher (more wattage). You have to be careful that you don't get lamps that will melt your tail lights if yours are plastic. If you have glass tail lamps, you have a little more room for error.
The wattage of the bulbs is written on the package. Go through the auto parts light section, find the same bulb base configuration and look for the higher wattage ones (provided your tail lights are glass). If you have plastic tail lights, as small as they are, I would suggest you remain with low wattage bulbs to keep them from melting. To improve what you have, clean the insides of the lens with a plastic polish and clean the reflective surface behind the bulb. The shinier and more reflective that rear surface is, the brighter your light will appear.
Also, all incandescent bulbs put out less wattage over time. Even a direct swap with exactly the same NEW bulb will often give some improvement.
Also, as the officer stopped you at night with ALL the lights on, make sure your charging system is 100%. Probably is, but always test it with a load on it (all lights, stereo, etc).
angela