I agree with turbodiesel. There is no advantage to removing it. Just leave it alone. Also, some people are mixing up the switch (sensor, has one wire connected to it) with the solenoid on the firewall (switchover valve, which has hoses connected to it.) The switchover valve MUST be clean internally or it will reduce power output by not allowing full fuel enrichment at the ALDA.
I have also heard the rumor that it cuts enrichment when decelerating. I have no concrete information to support that theory, and it seems to me that the I/P should be able to compensate for that by sensing the throttle position and ignoring the ALDA position. Right?
engatwork, your boost is WAY low. Spec is, IIRC, 13-14 psi. I'd adjust your wastegate up closer to 12+ psi and I bet you'll love the added power! That is assuming the wastegate is the problem...
EGR is evil on a diesel. It does nothing but crud up the intake while decreasing power and MPG. Here's a photo of my sister's OM603 intake charge pipe, just after the EGR valve. I tried attaching it to the post, if it doesn't work, it's at this URL:
http://www.meimann.com/images/mercedes/OM603_intake/pipe_before.jpg