When it comes to durability, Injen?s Evolution series can?t be beat! Some of our competitors use an inferior HDPE linear polyethylene to mold their intake systems. HDPE is cheap for manufacturing but doesn?t come close to the strength and durability of XLPE polyethylene. Injen strictly uses the superior XLPE crosslinked polyethylene and has 20 times the environmental stress crack resistance of HDPE, 10 times the molecular weight of HDPE, and 5 times the impact and tensile strength of HDPE. In other words, Injen?s Evolution intake systems are built tough and designed to last the competition!; XLPE Roto-molded Housing:, The one-piece sealed housing utilizes the all-new Injen Twist-Lock System to securely attach the 8-Layer Oiled Cotton Gauze air filter in place which eliminates the use of unnecessary parts and provides one of the simplest installations available. The EVO9004C housing also sports the all-new Injen Clear-View badge for a cleaner more aggressive under hood appearance.; XLPE Roto-molded Battery Relocation Tray:, The EVO9004C battery relocation tray is molded from crosslinked XLPE polyethylene and allows the airbox to moved to the font of the engine compartment for a cooler air charge and reduced restriction.