Julio it may have added a few horsepower, but like you said for the price it aint worth it.Another thing the oil that coats the filter gets sucked into the throttle body,i know from experiance.i had 2 k&n filters one ready for when the other was dirty.i would immediatly clean it then let it dry then spray on the oil and leave it.no matter what i done the oil will still get sucked in. plus you know something is wrong when they say right on the box the dirtier it gets the better it works.You know what that means,It means that the holes in the filter are larger to allow more air in .(along with dirt and oil) and as it gets dirty it fills in those holes and filters more like the regular filters do.
maybe you can talk the intsructors into doing one of those kits on a jeep and see how it works.jeep has built in cold air induction ,but it gets the air from ouside the engine compartment. then do some butchering and put a smooth pipe in where the ribbed part of the stock tube is.test different methods and see which performs the best.