Well the first thing to do is search these forums for your questions...
Exhaust Manifold - I have the etd manifold. There seems to be a wait on them, so look around, realnissan, ssautochrome, a couple other people are making some. Search for those...
Turbo - The consenus seems to be a T3/TO4E 50 trim .63 A/R Cheap turbos has one
http://store.yahoo.com/cheaptu....html for 589.00
Injectors - If your looking for low boost to start out on, pick up some used sr 370cc(purple top) injectors used. Can be found anywhere from 30-100 bucks...
Piping - Most people fab there own, or greddy has a kit for s14(intercooler & piping) you could make fir on a s13.
Downpipe - fab your own
Engine management - theres big discussions going on about this, search around for this. Anything from piggbacking safc, emanage, to ecu rre-write by jwt or full standalone from aem, or other standalone units...
Most importantly read everything here, and on zilvia, and freshalloy. Ka-t is somewhat new, and you can learn from people expierences/mistakes...