Performance modeling is a process where a representative nominal engine model is calibrated to the test engines as installed on the test airplane. Research initiated by Schweikhard and Marshall at NASA and further developed at the University of Kansas has shown that performance modeling is a viable and inexpensive alternative to in-flight thrust measurements or calibrated engines. Testing using this method has been performed by Kohlman Systems Research on twelve business jets. On one of these programs, both calibrated engines and a nominal engine model were available; thus verification of performance modeling was possible. Through this verification process it was shown that similar drag polars resulted from the two methods. A difference in drag was found to be no greater than 20 counts. This paper describes the methods used for the performance modeling, which includes propulsion modeling methods and flight test procedures. The resulting flight test data are presented.