truth is on an NA motor, only way the intake is going to make any more power is if you have either a tuned intake length, or a resonant AIR BOX. everything else you are loosing power, except at WOT around 10,000 rpms, which you rarely see on a street bike.
the difference between them is very minor... about the same performance between them and no filter whatsoever. on the street i would run pods over stacks just because theres all kinds of dust and shit that can wreck your motor.