My CAI is completely DIY , its a k&n cylinder oiled paper filter with mesh cover inside the stock air box which has the back cut out and extended thru the back wall into the cowl area cold air pocket. the air box is cutout with a dremel in a rectangular shape and then the side walls of the airbox is extended thru a cutout in the back wall and the whole thing is sealed of with black weather striping and rubber spoiler pieces. a peice of 3 inch PVC is cut and filed a little and pushed into airbox inlet to make the flange for the filter to mount to. the PVC fits perfect and tapps in with a small hammer. After this MOD alone the engine had a much deeper growl and the SC really woke up and started to scream after 3.5 k rpm up to the limit. IT made a noticable improvment in acceleration and performance most likely in to 10 to possibly 15 hp... the stock air filter and box is very very limiting and starves the engine of air when it is needing it most. paired with the one Ball Mod and an upgraded intercooler the improvement in performance is quite impressive ....... no pulley mod yet...... its on the bench with a new tensioner , crnk pulley, belt and colder plugs. just waiting for a time soon when i can put the car in frnt end service mode to also change the SC oil, and water pump and various seals, o rings, and other misc stuff that the 100k service would or should do. im replacing the water pump just because i dont want to wait for a failure..... same with tensioner and crank pulley, All these part are estimated to have served thier useful life at 85 k which is the approx mileage and FYI 180 degree thermostat was a great decision and is helping reduce excesive heat in stop traffic. ALUM billet expansion also a great improvement over stock plastic crap and while ur at it do the Pwr steering in billet alum too just get a good one with bottom muzzle.

rear wall cutout into cowl area with larger lower hole into lower box

box side extensions with diamond plate and flex tape, the rubber piece ontop was replaced with a piece that also goes down the side and seales against the back wall around wall cutout

box rear cutout

box rear cutout

pvc flange from outside looking into filter

upside down view inside air box

Sorry thought the air box was visible......yes thats also a DIY shock tower brace attached to my cravenspeed tower defenders, home depot right angle steel shaped ,tapped and drilled to fit with end brackets...... the eyes are also DIY printed and laminated at home and double sided taped on....... screw paying 30 bucks

 

10 to 15 hp... Not that I want to doubt you, but that's not the kind of gain you can throw out without a dyno test.

 

well i am just trying to illustrate that it was a noticable and im sure measurable improvment. gains of 1 or 2 arent really a noticable change. its simpy an educated guess by a seasoned wrencher, i aint payin for a dyno untill im done with pulley reduction, cam and port and polish (maybe) i am most likely gonna need a retune so thats gonna be in there then ..... the reference was also with one ball mod . probably only single digit but well worth the experiment, my CAI cost me under 50 bucks and my one ball mod cost the price of the elbow , a id/od pipe adapter and two wrap clamps. about another 50. ....Sounds awesome on hard accel. Performs as well as any of \the 250 and up CAI's. BUT I DONT disagree with you either........(says my logical brain)

 

probably more like 5 to 8 realistically...... the stock filter is a choke collar as the sound changes alot with alot more charged air.