I believe I have a boost leak from somewhere..... I only boost 13 PSI which seems low but I've noticed in first gear a WOT I overboost to 38 and sometimes I vacuum -38. Also when I'm going into the highway going into work I notice my car start to shake when I get to 4000 RPM mainly in 3rd and 4th gear. Getting a knock of 5.6 rarely but mostly 1.4-2.8. And suggestions on what might be happening and should I be worried? Clutch is worn and does slip but I don't think a slipping clutch would cause the car to shake and cause knock.