i have a 97 civic ex i plan to run 8 psi, if i get a afc how much would dsm 450 injectors really help. and if i get a afc will i stl need a missing link.

 

You need an AFC to control the larger injectors. More fuel is a must to boost your engine. You can't add more fuel with stock injectors (unless you increase the pressure = FMU).
You don't need a missing link with the AFC.

 

you use larger injectors so you can subtract fuel from them and also subtract the voltage going to the ecu from the map sensor. if you kept the stock injectors and added fuel with afc or fmu you will immediately get a cel.