You should be able to see a pronounced VTEC spike w/the OEM computer. No idea why you cannot.

What kind of dyno is this?

Here's a graph of a completely stock USDM ITR, showing the kind of VTEC spike that's typical on a stock car:



Mild upgrades on an OEM ITR can provoke a pretty wild VTEC spike, as seen in this graph of a car w/just normal bolt-ons: