Like the title says. My car should be making 18 pounds of boost and it's at about 12. I changed the belt but that didn't help. I noticed that the connection on the pcv looks like it's leaking oil. I talked to my tuner and after reviewing my datalogs, he said I have a vacuum leak. I am gonna start with the pcv. Could that cause that large of a drop in boost, or it might be leaking somewhere else?