I just did the wastegate modification to my 92 300D - It was by all accounts a success...as for the boost pressure it appears to be satisfactory ( my all purpose shop vacuum pressure gauge only goes up to 10 on the positive side and it pins it ). I took the control signal for the wastegate actuator off of the intake and it seems to work fine.

! Please note that I did shorten the rod length by the 10 mm suggested earlier in this thread but actually that was not necessary nor helpful unless a person has the 6 x 1.0 metric die that is required to cut additional threads on the shaft. The reason for this conclusion is that before I cut the 10mm off the shaft the adjustable tip was able to bottom out on the threads with the locknut removed and this was also the case after I cut the 10mm off. the end result is this... with the locknut in place which it is necessary there is aproximately 3mm of shorter rod length that is required to achienve the closed and slight pretension load on the wastegate arm ( at rest position of wastegate)... so what I did was I placed one flat washer and one lockwasher on each of the threaded mounting shafts of the actuator and then offered the actuator to the mounting bracket this effectively shortened the rod lenght the required distance without the need for the die ( the only one that I was missing from my set... isnt it alway like that ). hope this helps someone in there efforts.

I have another problem ( as my poor power was only moderately improved by this modification ) - I believe it stems from the fuel supply side... I will detail what I know here and if anyone can provide any input it would be greatly appreciated.

1) the Alda is defintely getting complete signal from the intake manifold ( ihave it run direct form maniflok to ALDA diaphram.
1.1) I checed the ALDA diaphram to ensure that the diaphram is infact holding pressure ( not leaking internally )
2) the fuel stop lever at idle hovers near the stop position and raises up as the RPM increases ( no I did not change the fuel stop valve ) - ( someone else did before I got the car )... the car shuts off fine with the key as it always has.
2.1) the fuel stop lever has always ( for the last two years ) since I purchased the car had this same behavior ( in that the lever oscilates on Rpm increase and decrease as in the case when I am under the hood and applying light throttle pressure and then allow it to snap back to idle.
2.2) When I first got the car and up unitl about 6 months ago the car had amazing power right off the line and right through the power band ( almost unnaturaly so ) as compared to my 91 300D and it got 34 + mpg ( now gets 27 mpg at best ).
2.3) back to current manifestations... if I wire up the stop lever in the full run position ( which is not as far up as the 91 is in while running ) I get noticeably better low RPM power but still not fabulous.
3) yes I have wired the throttle butterfly in the open position and I removed the vacuum supply at the vacuum pump and plugged it thereby eleminating completely any vacuum supply to the whole computer related control system

So does anyone have any understanding of the function of the internal linkage of the fuel supply control side ( ie: the alda - fuel stop lever and electrical connector immediately behind the fule shut off valve ) of the injection pump. How they relate in a fashion that may at least in principal explain the situation I have. To clarify I have about a 17 sec to 60 mph from a stop to full throttle acceleration. This time was only improved by about 5 seconds by doing the modification ( before the modification it was about 22 seconds ).

My thought is to change the fuel shut off valve as it seems to me that must have been put in wrong but it does not explain why it was working extraordinarily well with it installed in this same functional state.

4) last detail that might be helpful is that the car often but not always throws substantial black smoke on downshift and heavy acceleration... the experience can be equated to the city bus on takeoff ( we have all at one time or another been behind them...not a nice experience to be sure )

any thoughts will be greatly appreciated

Thankyou one and all