We present new results from our study of the X-rayed outflow of the z = 3.91 gravitationally lensed broad absorption line ( BAL ) quasar APM 08279+5255 . These results are based on spectral fits to all the long exposure observations of APM 08279+5255 using a new quasar-outflow model . This model is based on cloudy cloudy  is a photoionization code designed to simulate conditions in interstellar matter under a broad range of conditions . We have used version 08.00 of the code last described by ( 20 ) . The atomic database used by cloudy  is described in ( 19 ) and http : //www.pa.uky.edu/ \sim verner/atom.html . simulations of a near-relativistic quasar outflow . The main conclusions from our multi-epoch spectral re-analysis of Chandra , XMM-Newton  and Suzaku  observations of APM 08279+5255 are : 1 ) In every observation we confirm the presence of two strong features , one at rest-frame energies between 1–4 keV , and the other between 7–18 keV . 2 ) We confirm that the low-energy absorption ( 1–4 keV rest-frame ) arises from a low-ionization absorber with \hbox { log~ { } ( $N _ { H } / { cm } ^ { -2 } ) $ } \sim 23 and the high-energy absorption ( 7 - 18 keV rest-frame ) arises from highly ionized ( 3 \lesssim \hbox { log~ { } $ \xi$ } \lesssim 4 ; where \xi is the ionization parameter ) iron in a near-relativistic outflowing wind . Assuming this interpretation , we find that the velocities on the outflow could get up to \sim  0.7c . 3 ) We confirm a correlation between the maximum outflow velocity and the photon index and find possible trends between the maximum outflow velocity and the X-ray luminosity , and between the total column density and the photon index . We performed calculations of the force multipliers of material illuminated by absorbed power laws and a Mathews-Ferland SED . We found that variations of the X-ray and UV parts of the SEDs and the presence of a moderate absorbing shield will produce important changes in the strength of the radiative driving force . These results support the observed trend found between the outflow velocity and X-ray photon index in APM 08279+5255 . If this result is confirmed it will imply that radiation pressure is an important mechanism in producing quasar outflows .