Comptuers

Computers

The stock turbo fuel injection system will support only around 275 horsepower before the injectors are maxed out. Once you reach this point you have a few choices:

JWT 450 package: Uses an 88-89 (turbo or non) comptuer than JWT modified to run 420cc/min injectors with a 1993 Ford Cobra air flow meter(cheaper, more reliable, and less pressure drop than stock unit). This also gets you the tweaked JWT fuel and ignition timing maps, which are very nice. At a cost of $600 (plus $250-600 for the injectors and around $200 for the Ford air flow meter) it is the cheapest way to get lots of extra power capacity in your fuel system.
Reprogram your own computer: basically what JWT does, do it and tune your own Nissan computer. The basic information you need to do your own hex editing and prom burning is available here.
Stand-alone systems: Motec, Electromotive, SDS, Haltech, and others. These are stand-alone fuel and ignition systems that are fully programmable and can use any components you want(ie. any size injectors). They require lots of work and knowledge to install, more than most people posess. But they are the most adjustable and best way to go. You can get into an SDS for around $1000, Tec3 for around $2000, and Motec starting at $3k. Some of these systems will require all new sensors and lots of custom made parts. But compare to the cost of the JWT 450 package and you'll see that for just a hair more money up front you can have far more potential down the road.
FMUs: Highly not reccomended. These are fancy fuel pressure regulators that raise fuel pressure faster than the normal 1:1 ratio. Normally at 10psi manifold pressure your fuel pressure will be the set value plus the 10psi to account for the manifold pressure. An FMU will raise fuel pressures more than 1psi for each 1psi of boost - ie. you'll be running 20psi above normal fuel pressure at 10psi manifold pressure. While they can be made to work, they are a band-aid and not suitable for any significant gains in power. Avoid at all costs, they are bad.