As mentioned above, the SAOSAC HRMA model serves as the basis for our PSF analysis; thus we are dependent on the fidelity of this model for comparison to XRCF data and for predicting on-orbit results. We chose to use SAOSAC for the PSF simulations because it is the most comprehensive model of the HRMA; the subtle features and interesting azimuthal structure of the PSF is not modeled by MARX. The PSU CCD simulator ``acis_sim'' (described in detail in Section 7.1) was designed to interface with MARX to exploit the excellent modeling capabilities of the MARX package. We chose to preserve this design for the PSF simulations; thus we use MARX to read the SAOSAC rayfiles and propagate the rays to the surface of the ACIS chips, relying on MARX to supply the appropriate geometric transformations and to account for the tilts and spacing of the chips in the ACIS camera. The acis_sim program uses the ray positions at the chip surfaces and the direction cosines to project the rays to their interaction points in each CCD. It generates event lists, which have been processed in this analysis with the Event Browser package (see Section 7.2).