you'll get 15hp out of a CAI...when i get 100hp from a CF hood.
personally, i can't tell b/w a CAI and SRI in performance. soundwise, the SRI is definately more noticable. i dont' know if it's a mind thing when people claim it's night and day between the two. a lot of people will mention the air temperature difference. while the air temp under the fender will obviously be lower than behind the battery, the variance is negligible in hp difference according to my findings. anyone else care to disagree, feel free to post your own findings. but i know on my car, if there has been a difference, i apparently have missed it.
most CAI cost around $200 for the intake tube plus maybe $50 for the filter. i'm sure you can find one cheaper on the internet. dont' expect too much of a boost in hp from an intake. at most you should get 5hp out of this mod.