I have modified a few sets of front upper A-arms to provide more caster adjustment. I run 6.5 degrees on my GT5, I also found tire brand choice made a big difference. I fabricated a jig to set the a-arms up in and ensure geometry.
The modification is well documented;
http://pantera.infopop.cc/eve/...0042044&m=9830021654
If you don't already have wheels and not using original style Campi's then you are more open to fabricating longer a-arms and modifying wheel offsets to compensate like the Si's had.
Julian
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.