If your going for an all out race 240SX then a standalone system is the way to go. When you use a standalone such as the AEM you gain the ability to completely tune your car not just air and fuel unlike a piggyback. Although a piggyback is cheaper and it will do the job a standalone can make things a lot more simple especially if you go with the plug and play AEM Standalone because all you have to do is remove your factory ECU replace with the AEM standalone and enjoy as well as being able to tune with your laptop.

AEM's Plug & Play Engine Management System (EMS) plugs directly into a vehicle's factory ECU harness and requires no additional wiring or hardware. Windows™ compatible software (2000, XP, NT, 98, 95, ME) makes the task of copying, viewing and manipulating data as simple as a click of the mouse. An integrated tuning wizard allows users to create a base map specifically for a car's configuration, regardless of what type of injectors, sensors, coils or other changes have been made. The AEM EMS's infinitely adjustable software allows tuners to program virtually any combination of engine control, power adders and auxiliary devices, and accurately delivers proper amounts of fuel and correct ignition timing for any boost level or operating condition.