I think one of the things you have to watch out for is that these "sport" air filters work their magic by allowing for more air flow by being more porous, which means they do a comparatively poor job of keeping larger particulate matter out of the engine, not a bright idea. If you put your car on a track for a few hours of racing, I guess putting in one of those filters might result in some marginal benefit under those circumstances, otherwise for regular use in the city or on the highway I'd avoid them.