actually, no it doesnt. DBAD, something else is soaking up your low end (perhaps lack of an equalizer, perhaps improper pipe sizing, ect), not the straight pipes.
i wish we could get a sticky for this, but since we dont....here goes again:
backpressure means next to nothing on a 4-stroke motor (other then the fact that its dependent on scavenging). what you need to concern yourself with is exhaust scavenging. this is the exhaust pulses tendency to pull each other out of the exhaust pipe. any constrictions in the exhaust system (cat converter, muffler, crush bends, sharp bends, improper pipe diameter, ect.) can reduce exhaust scavenging.
generally speaking, smaller pipes move your power curve towards the lower RPM range, bigger pipes move it up. dual exhaust pipes should be slightly larger then half the pipe size of the proper single exhaust diameter. any time you run a true dual exhaust you will loose low end power without some type of equalizer pipe.
im running 2" true duals with tiny 25" cherry bombs on my 3.0 and was actually surprised to notice a small boost to the 23-2500rpm range.
its all about tuning it to get the desired result.