With the undertray body-colored- especially the sides that are visible without getting underneath, the car may end up looking chunky; that's why they had a black painted undertray from the factory. If you can, find a photo that you (or someone else) can play around with on Photoshop before you do something expensive you ultimately won't like.
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.