for an NA with basic bolt-ons, it'll increase hp and air flow the bigger piping you go. but up to a point. after about 2.5", you'll start losing backpressure and ultimately lose tq on the bottom end.
the max that you should go on a boosted motor is 3". anything bigger will have the same effect.
canister (straight through) design has a better air flow and loud depending on type
chambered (oem type) design is much quieter but the air flow is more restricted