For the most part - unless you change compression ratio, Cam profile/timing, valve size, cylinder head port shape/size, intake runner shape/size, ignition timing and fuel curve (last two controlled by computer algorithms) all of which determine the engines volumetric efficiency - changing intake and exhaust has negligible effect over the entire torque curve. It may have an effect to say the amount of torque at 3100 is increased but the amount at 2800 is decreased - no real gain and no way to measure it - seat of pants is NOT reliable because other senses (sound smell etc) effect your opinion (sounds faster and smells leaner so must be right?).
AND we drive at 1100 to 3500 - that range works best with small diameter (thus higher air velocity) intake. Increasing the size of the intake has the same volume of air moving much slower - less effective at lower RPMs. Just compare a 360 magnum head to a 360 head - the magnum makes more torque sooner than the 360 - and the ports are noticeably different!
If you have a 1/2 pipe supply a faucet with a 3/4 inch hose attached - would you get more flow by hooking a 1" hose to it? NO - same gallon per hour, as the faucet (just like the compression ratio, cam profile/timing, port shape and volume) is the limiting factor.
J Wm Bishop EA, ASADE
How to start an online argument - express opinion - wait.