There are 2 kinds of fuels injectors: high and low impedance

High-impedance injectors, also called saturated fuel injectors, are sent a 1–1-1/2-amp current signal to open, and that current stays on until the injector closes. That low-amp current keeps the injector temperature lower, which makes it more reliable; that's why the high-impedance design is the most common injector style for OEM applications.

Low-impedance injectors, also called peak-and-hold injectors, are sent a more powerful electrical signal, usually around 5–6 amps, to open. Once open, the signal drops to 2–3 amps. This design will open and close more quickly, but will also run hotter. Most injectors that flow more than 70 lb/hr are low impedance.

The type of injector you'll need for your application will vary depending on your ECU and your power levels. If high fuel demands have you wanting low-impedance injectors on an ECU meant for high-impedance, you'll need to run resistors or a driver to compensate for the different current demands, otherwise heat will build up and fry your electronics.

The Volvo 940, 760 and 740 turbos on the 2.3 engine were low impedance injectors. The 850 turbo injectors are high impedance. If you opt for low impedance you need a resistor pack to keep the wiring from sizzling. On a stock late model 240 unequipped electrically this adds a lot more hassle.

go here to see what cars use which injectors

http://users.erols.com/srweiss/tableifc.htm

scroll down to find the injectors common in volvos