enuff bitchin! im not to sure how the Corvette system works but hondas VTEC system has only 1 set of cams (2 cams in total). each cam has 3 lobes but 2 different lobe grinds on the cam. the standard 1 for nortmal driving and then the long duration one that kicks in for spirited driving.
the cams dont change timing at all, instead it is the rockers that change to allow the cams lumpy lobe to kick in.
a pin is hydraulically shot through the 3 rockers (yes 3. one in the middle of the 2 normal ones for eack valve) that lock the 2 outter rockers to the one in the middle where the lumpier lobe runs. thus the lumpier grind now is the only rocker that has contact with the cam and the valves now open and close with the longer duration and higher lifting grind of each cam... simple!

this is the same on both exhaust and intake cams

the pin is controlled by the engines computer and is set to a certain rpm. you can buy aftermarket units from apexi (AVC-R: acutator valve controller type R) and many other companies around the world that allow you the driver to change at what rpm the lumpier cam kicks in.

hope this helps