Open pod or drop-in? Which is better?

when you say open pod do you mean the intake air filter will be exposed under the hood? If so i would go with a Green drop in air filter. Because if the air filter is exposed to under hood temps you will lose so power. But if you have the money i would go with the Racing Beat Intake and Ram Duct.

Ok. If i just replace the stock filter with a drop in like a K&N replacement filter, does it work?

yeah anything is better than stock but you wont feel any hp gains. I think K&N says like 2-3hp. I bought the Green Filter and it felt a little smoother. i am getting between 21-22 mpg. soon i am moving up to the racing beat intake and duct