Below is a general manufacturer product group description. Please note the information below is not item specific. Item specifics are above in product details.

The first of many expansions into the fueling accessories market to complement our diverse fuel delivery products is are two innovative rail-injector kits for the Subaru WRX, STi, and other EJ20 and EJ25 Subaru engines. The new kits come in 2 styles: Upgrade Kit and Conversion Kit.
The Upgrade Kit is for applications that already utilize top feed injectors. This kit eliminates the poorly designed OE rails that allow cylinder-to-cylinder pressure variances. The DeatschWerks kit includes injectors and rails that are engineered to work together and provide consistent fuel supply over a wide range of flow rates and pressures.
The Conversion Kit is for applications that utilize side feed injectors. This kit, in addition to supplying a consistent fuel supply, allows the customer to run top feed injectors that are less expensive, tune better, and are available in many more flow rate options.
Both the Upgrade Kit and the Conversion Kit include injectors ranging from 750cc to 1200cc and are engineered as a system where the injectors, rails, and mounting hardware all work together to integrate flawlessly into the existing OE manifold and mounting points. In addition, both systems are fully anodized for e85 compatibility; feature large bore -6AN fittings; and include everything needed for a drop-in fitment.