The most simple,but least effective is to switch from the three watt bulbs to five watt bulbs. I think the boys down in Texas (Space city Panteras) have a website that shows how to add some serious illumination.
PANTERA INTERNATIONAL
A DE TOMASO CAR CLUB
Presents the De Tomaso Forums
The On-Line Meeting Place for De Tomaso Owners and Enthusiasts From Around the World
Clicking on the banner will take you to the sponsor's website.