The i-vtec is controlled by the so-called "intelligence"
but its actuallie the ECU mapping, just like how a fuel regulator
works without hesitation when u "needs" it.
Definitely the response in i-vtec is better than vtec, but not the
SiR
If u seriously modding ur car, it also dont matter much, but u can
go test the new Accord i-vtec 2.0.
the response is extremely good for a sports sedan and i take my hat
off Honda as the car is built with quality unlike the past
accord...its like a Japanese BMW
go give it a test drive and u know what i mean. 
