[Elecraft] K3 S meter vs P3 S scale

[Jim Miller KG0KP]

Seems to be quite a difference in the readings between the P3 showing S 
scale and he S meter reading on the K3.  The software in both is up to 
date(recently at least).  The difference is quite significant with the P3 
being considerably lower.  Maybe I don't know how to read the two meters. 
On the K3 I read the mostly steady peak reading excluding the static crashes 
if any.  On the P3 using clear frequency noise as an example, I tend to read 
the "average" of the noise trace.  Should I be reading the peaks 
(disregarding static crashes)?

Is there a calibration I need to do?  To which and where is the procedure 
spelled out?

Will I will need to order the new XG3? (please)

TIA, de Jim KG0KP