This is for a FD.....

I see many people have 1600 or 1680 secondary injectors.
I know you need a different fuel rail, a fuel pressure regulator, and pigtails. What else am I missing, and what are pigtails?

 

Your missing resistors or the better route, a high impedance to low impedance (peak&hold driver) converter box (which is what I use).

Depends how much you want to spend and if you care about fuel rail looks. 1600's and 1680's are the same injector, they're just different ratings for fuel pressure.

You can get something like this which I think is the best looking one (I have this one)...

http://www.cj-motorsports.com/catrx7s1.htm (Base /w regulator, buy injectors separate 550/1600's , I have my old 550's if you go this route, only about 5k km on them before I went bigger)

Or a cheaper option is... which keeps your oem primary rail and injectors and comes with the 2 1600's...

http://www.rx7store.net/product_p/extremefuelfd.htm

Pigtails are just the connectors to splice into your harness since 1600's are top-feed and use the Bosch style connector.

However, I'd like to mention this was not related to your leaning out as the problem was fuel pressure dropping. Your injector duty cycle was still safe.

thewird

 

You are likely right. Going to a larger setup allows for more head room if I need to upgrade to a single, more boost, plus it allows for an aftermarket FPR, and gets rid of the other solenoid you mentioned.

If the engine is coming out I might as well do it now

 

Will the fuel pump have enough capacity to supply the bigger injectors?