Unity3d latency question

I don't have an oculus rift currently to test this out but when you look at the main thread and it says 6.5ms, does this just add on to the default latency the rift comes with? So say if the rifts latency alone is 20ms (don't know), then the total would be around 26-27?

I know this was talked a lot about before but I'm not finding those discussions atm. Mainly asking since if all graphic settings are maxed the latency goes to 20ms though this could be because i'm lagging and if i swapped my 7850 out with my 290 the ms might drop. Have to wait to for new psu to test that.