What is the LDA on the IP?
LDA translated is Manifold Pressure Compensator, the flying saucer appendage on top of the IP.
I like how this page explains how to tune it:
http://dodgeram.org/tech/dsl/more_power/Power_ve.htm
Nice description and cutaway:
http://vwdiesel.net/forum/index.php/topic,30340.0.html
More tuning tips, with helpful photos:
http://vwdiesel.net/forum/index.php/topic,645.0.html