Gauss |
Here are the relevant FAQs.
Power Attack when using a Lance One handed FAQ
Strength and Power Attack with 2handed weapons treated as 1handed weapons FAQ
What the answer is depends on interpretation. Some people (such as myself) believe that the two FAQs are contradictory.
However, the strict answer is that you get 1.5x Power Attack because the Lance FAQ states you do, but that you do not get 1.5x Strength bonus because the Lance FAQ does not state that you do.