In the past week I've done research on what CAI gives the best performance increase. By far this K&N is the best. The test were done by an independent group (dyno sheets available) who also tested several other mods for the new 6.1 Hemi Challenger.

K&N 63-1114 Air Charger Air Intake Kit

http://www.amazon.com/gp/product/B000CO826S

Amazon.com has it real cheap.