I didn't actually see a noticeable difference one way or another but this could be where our motors differ. You're may be right for your car, but I'm not so sure. Most motors are most efficient a little below peak torque, but the torque "curve" on your motor looks more like a line, in part thanks to VTEC.
On my motor, peak torque occurs at something like 5200rpm, so friction aside, I'd be best off shifting in the upper 4000's. I think friction increases with the square of the speed though so at some point it outweighs my efficiency gains with rev'ing higher to get closer to peak torque.
Brake Specific Fuel Consumption (BSFC) Maps - EcoModder
^ Your BSFC is probably something between the Saturn DOHC's and the Toyota 1ZZ-FE. The Saturn is most efficient around 2500rpm and the Toyota, at 3000, so ideally you'll be accelerating with the pedal down around (or just before) the point where pushing it farther doesn't give significantly more power, and trying to keep the motor in that range.
EDIT: What instrumentation do you have?