tkb30, u just need to feel the rush of speed when your vtec opens. not necessary mind blowing acceleration but you'll feel a slight urge in moving forward as the RPM climbs as compared to other engines whereby the car loses acceleration as they near redline. besides, even with stock exhaust, you can hear a slight different exhaust note as you enter vtec zone.
samson2266, i don't know about 4500rpm but certainly my SOHC VTEC does pickup revs after 5500 rpm.
as for fuel consumption. after hearing from u guys that has really bad fuel consumption, i pumped full tank 2 days ago and start to rev really hard at every opportunity just to "find out" how bad the consumption can get. and yes, my meter shows 160km travelled and the fuel gauge shows alittle below half indication. i'd estimate i can travel till about 330km before the light comes on. however, normally i can easily do about 430 to 450 for a full tank. this shows that heavy revving till vtec really affects your fuel consumption considerably high.