It doen't get much more simple than this!!!We all agree a turbo needs exhaust gases to function!!, right??? Well you can not get exhaust gases intill there is RPM's and as the rpm's increase so do the exhaust gases!!! This is why some cars with after market larger turbo's dont spool intill 3500-4000 Rpm, because there is not enough exhaust to spin the turbine untill upper rrrr's, thus creating lag because of the back presure from the unit!!!!!!
I do see your point about Climbing an inlcline, to a degree. However this is a an exception the rule, when ever you peg the gas to maintain rpm's there is an increase in combustion how ever the added stress from the incline doest allow the rpm's to climb as the normally would!!!!
Now do the same thing but at 1500 rpm's and watch the boost gauge will it climb?? I honestly don't know!!!!
However lets not stray from the statment: That a turbo is not Rpm dependent!!!
Because if your car is just sitting there not running I am sure the turbo is not spooling up!!!
