  SAX J1808.4-3658 has a 2.5 millisecond neutron star rotation period and
exhibits X-ray pulsations due to its rotating hot spot. Here we present an
analysis of the pulse shapes of SAX J1808 during its 1998 outburst. The
modeling of the pulse shape includes several effects, including gravitational
light-bending, doppler effects and two spectral components with different
emissivity. In addition we include the new effects of light-travel time-delays
and the neutron star's oblate shape. We also consider two different data sets,
with different selection in time period (1 day versus 19 days of data combined)
and different energy binning and time resolution. We find that including
time-delays and oblateness results in stronger restriction on allowed masses
and radii. A second result is that the choice of data selection strongly
affects the allowed masses and radii. Overall, the derived constraints on mass
and radius favor compact stars and a soft equation of state.
