Right fuel rail pressure?

[dammad]

I have a 6.2L Yukon. It has low MPG, around 9.6 city. I checked the fuel rail pressure via OBDII and got 300kPa/43PSI. Does anyone have what it is supposed to be? Seems low to me.

 

[dammad]

Any body?

Also does anyone know what the MAF is supposed to read at idle and 2000 RPM? (also through OBDII)