Review on 🚀 K&N Cold Air Intake Kit for 2004-2005 PONTIAC (Grand Prix) – High Performance, 50-State Legal: Boost Horsepower - 57-3049 by Joshua Albright

This kit was pretty easy to install - I took my time and it probably took around 2 hours. I didn't notice any difference in the sound after starting the engine - but that changed as soon as I drove it. After reaching 2500 rpm you are greeted by a completely independent and difficult to describe fan noise. It's not a "whistle" as some say. It's more like the sound of a turbine - and I think it makes sense because that's what it is! I noticed a significant increase in throttle response. Without a dynamometer, it's harder to pinpoint horsepower, but the car feels snappier. If there's an increase, it's probably less than the advertised 15hp, but the other benefits I've mentioned make it worth it. The fact that the sound changes so much is an indication that the stock airbox/filter was restrictive. I believe this mod is a necessary utility mod (one of several required) to work with the smaller SC pulley.