The Stock Driver's side Head on 03-04 Cobra Mustangs (and most DOHC 4.6L Applications) runs hot. This is because of Ford's failure to provide adequate cooling to the #7 and #8 cylinder jackets on the driver's side head creating hot spots/steam pockets in and around the cylinders (aiding in potential detonation). By creating a direct cold path from the radiator to the hot cylinders, coolant flow in this area in increased dramatically.All new from LFP; introducing the Gen 2 Head Cooling Mod. This Generation 2 design uses an O-Ring seal and a retaining plate to secure it in the cylinder head. A benefit to the newer design is that it can be installed on supercharged applications (03 Cobra-style set-ups) without removing the supercharger or the transmission. Additionally, this newer design allows more flexability for customers who desire to use AN fittings and stainless steel braided hose or other hose variations. The Gen 1 cooling kits are NOT being phased out and will still be available. Due to differences in the earlier 96-98 cylinder head castings, the newer Gen 2 kits are not a direct fit due to the lack of a tapped casting boss for the retaining plate.**Once this modification is installed, both cylinder Heads will be flowing coolant through a restriction averaging .350, thus maintaining Direct Cold Radiator fluid through both heads.**This kit can be installed from the top of the car, with the Blower Removed. This does NOT require removal of the transmission.