I have a MOPAR CAI on my 09 6 speed SRT. It definitely moves some air. No oil in the filter on the MOPAR unit.
I'm not a lawyer, but I can't see how the MOPAR CAI would void the factory warranty.
You can install the unit yourself in about 30 minutes. It's not difficult at all.
I would say the CAI is your first step in improving performance, followed by a free-flowing aftermarket CatBack exhaust (my preference is for the Corsa). Once those two items are installed, if you get a DiabloSport Predator programmer and load a 91 octane canned tune in your baby, she'll wake up to the tune of 10-20 more RWHP than the stock system.
Diablo doesn't have tunes out for '09 6-speeds yet, but are due out any day now.

I got my CAI from MoparSuperCenter, and my DiabloSport Predator tuner from
HighHorse Performance (limited time offer for the programmer, USB to Serial Port cable, external power supply/charger, a free stage 1 tune and free shipping - check thier site for this offer). Those vendors had the best prices / deals I could find on those items. You could also add some braided stainless steel hose to the CAI as a dress-up. I just need to swap out the exhaust systems and I'll be set on the basics.

Hope this helps.