Turbo must be checked with a load on the engine. (eg driving test on the road) You can pick up a boost gauge 0-20 and tie in with a "T" fitting off the manifold the line that goes to the ALDA to ensure your getting proper boost. Part stores have a combined VAC/PSI gauge its about 30 bucks. It might only go to 10 but it's in the ball park, about 8 feet of of 1/4 inch hose and a T-fitting (plastic will work). you'll need to cut a short piece of hose (about 4 inches) to connect the T fitting in line with the line that feeds the ALDA.

__________________
92 300D 2.5L OM602 OBK #59