Although the Subaru WRX STi is globally renown as one of the best foundations to
build-on for just about any form of motorsport, the fact remains that it still poses a
handful of obstacles when it comes to generating substantial power with the flat-four
boxer engine. One such obstacle is fuel delivery. From the factory, the 2004-2006 STi
came equipped with unconventional top-feed fuel injectors. While there is nothing
inherently wrong with the side-feed injectors in the factory application…the selection,
quality, and performance of higher-flowing aftermarket side-feed injectors leaves
something to be desired.
The solution to the problem is a logical one: eliminate the side-feed injectors and
rails altogether, and go the ‘top-feed’ route. Doing so opens up plenty of options for
larger, better performing injectors that will provide the additional fuel required in
higher horsepower applications (while still maintaining OEM idle quality and
drivability). However, the conversion to top-feed injectors poses its own set of
challenges. In the past, to complete the project one first had to source the Tumble
Generator Valves (aka TGVs) from another Subaru application that came ‘top-feed’
from the factory (or WRX-specific TGV deletes), as well as the top-feed injectors
and WRX top-feed injector connectors. Once all of the parts were sourced, the
side-feed gear had to be removed and the new parts swapped over. The hassle
associated with the conversion proved to be a deterrent for many STi owners.
After numerous requests, T1 developed the Side Feed Conversion Kit for those who
did not want to be constrained by their side-feed injector setup. This simple solution
retains the factory side-feed TGVs, but replaces the factory side feed rails with black
anodized / CNC milled 6061 aluminum top-feed rails and spacers, which are secured
by 8mm stainless-steel allen bolts. The kit also allows the use of any of the Injector
Dynamics line-up of top-feed injectors (ID725, ID850, ID1000, & ID2000). As an
added benefit, since the entire line of Injector Dynamics injectors are high-impedance,
there is no need to retain the resistor box or use any peak-and-hold injector drivers.
While the T1 Side Feed Conversion kit (thankfully) solved one large issue, it still left
the installer to their own devices to plumb the lines that feed fuel to the rails and
return it to the tank. This meant sourcing the right fittings and proper lines, measuring
(and re-measuring), cutting, crimping, installing, and hoping for the best. Not satisfied
with providing a partial solution, we are happy to announce that along with newly
redesigned billet rails, the T1 Side Feed Conversion kit is now being offered with the
option of fuel feed lines to make the conversion a true and complete solution for our
STi customers.
The new T1 Feed Line Kit utilizes RedHorse 6AN performance hose that feature a
lightweight black nylon fiber outer braid over a durable rubber core, with a maximum
pressure rating in excess 300 psi. The pieces come pre-cut and fitted with black
anodized RedHorse swivel hose-ends, and are ready to install right out of the box.
The kit is designed to plumb the fuel rails ‘in-series’ as it comes from the factory. This
routing method ensures that no vapor pockets will form in the fuel rails or lines. The
Feed Line Kit is specifically designed to be used with the T1 Side Feed Conversion Kit,
and is compatible with all fuel types.
Products 
T1 Subaru STi SFC Feed Line Kit
