ive searched but couldnt find anything good for nothing search. well i was wondering why people run different kind of injectors as there primary and secondary. what is it good for??

 

For bolt ons (like you) just an s-afc and a fcd is usually enough. But for more than that people usually run stock in the primaries, then either 680 (GSL-SE) or 720 (aftermarket) in the secondaries. A lot of the big guys run 720 primaries (smaller injectors atomize the fuel better at low flow rates resulting in a smoother low end) and 1680 secondaries.