Acceleration time should be around 12-13 seconds assuming you are near sea level (and yes, it was the OM603 that was in the 10's). The head gaskets were not fixed by 1993, my 1993 got a third head gasket after I bought it - usual blowout ahead of the #1 cylinder. Timing chain stretch is a biggie, there was a TSB on this issue,
click here. A new OVP cured the intermittent dead tach / no boost problem on mine.
Complete service records for the 1993 300D, after I bought it, are at this link (PDF file) :
http://www.w124performance.com/images/cars/misc/93_300D/1993_300D_Service_Record_pub.pdf
Photos before & after:
http://www.w124performance.com/images/cars/misc/93_300D/
Pics of the head gasket job:
http://www.w124performance.com/images/OM602_head/
Wastegate conversion:
http://www.w124performance.com/images/OM602_intake/
