On the V-AFC, what does adjusting the "V/T unmt" do? Does is control the A/F mixture at the moment of VTEC engagement and disengagement?

 

I think it adjusts the amount of fuel enrichment between where the stock ECU would engage VTEC, and where you have it set.
Example, if the stock computer engages VTEC at 5500 rpm, and you change it to 5000 rpm, when VTEC comes on at 5000 rpm, you are still using the non-VTEC fuel maps in your ECU. So, to get around this, you can bump up the fuel during this 500 rpm period until your stock ECU starts to richen the mixture itself.
Don't quote me though.
Jay