The boost elbow on the TST setup is a little brass 90degree elbow. It sits between the engine(attached like a boost gauge) and the wastegate so that the wastegate knows when to activate based on boost level. When you bomb the elbow it fools the wastegate into thinking you are generating less boost than reality. This allows you to achieve higher boost like 37PSI before the wastegate opens. I'm not sure if the Banks kit has the same elbow.