new engine

question, i just dropped an imported i would say 89-90 or soj-spec 7mgte into my 87 ma70, so ive got everything hooked up and have been running 6 pounds of boost, ive checked all my vacuum lines the only thing i can think of is maybe the guage or pressure sensor is in need of calibration or replacement any suggestions? also after i get this problem straightened out im wondering if a 3" downpipe and exhaust would be worth hooking up to the stock elbow which is only 2.5" or where can i get a bigger elbow??