Well the K&N is less expensive. Seems that the owners of both brands are pleased. I haven't seen a dyno of the K&N yet, but here's one of the Volant:
Volant CAI Dyno Results.. Both will have the advantages of a smoothed intake and enlarged filter area conical filter. The Volant draws air from the factory spot through the wheel well. The K&N does the same, but without the box, just a heat shield. With the Volant you can add the ram air scoop too ($125.) As far as the exhaust questions go, bit hard to say since I haven't experienced either Gibson or Banks, I'm a Flowmaster guy.
