If it is a US spec car it has headlights unlike any other MB of that model in the world. The very best light improvement you can do is to install the headlights that were standard on the car for everywhere but the US, the so called Euro lights. They not only put out much better light pattern without disturbing your wiring, they look much better as well (click the 87 300E logo in my signature for a picture of Euro lights. The light pattern is identical to the newest MB US legal lights.
The main downside is the cost - about $400 - and worth every penny. The PIAA and Hyperblues have been discussed in lots of threads, and don't really seem to last long or put out the claimed light (lots of tech reviews in the archives). Check the search button for Euro Lights for LOTS of discussion on these, as well as overwattage bulbs and wiring. The most overwattage I would go on any lamp without new wiring and relays is 80 watts hi beam.
2003 Firemist Red/grey leather SL 500
2015 Palladium Silver/black mbtex GLK 350
1987 Smoke Silver/burgundy mbtex 300E Sportline (SOLD)
Click to see 87 300E