1, Best one? (personal pref)
ie F sport intake looks stock and not as loud as a CAI (F sport intake is not the same intake from a F sport)
injen/K&N etc is nice loud but exposed
prices vary from 300-600 K&n~to F sport
2.Easy to fit? ( most of thm are)
3.Best power? (on a 250 it will make no difference)
4.Worth it? (if your after sound yes if anything more than that no)