Currently I'm running 2X550's and 2x720's with a walbro rewired, BNR stage 1 turbo S4, Greddy FMIC, S4 jspec motor stock ports. Running 10psi boost I was reaching 11.5-11.8 which I think should be ok, but when I turn it up to 11-11.8psi boost I can see the wideband blip to low 12's at higher rpms. Thats with the HKS S-AFR turned to almost 25% 5000rpms and up

I want to be able to run 12 psi safely with A/Rs in the mid 11's. I've read around and some say that I can run 4x720's and should be fine, But since I have some extra 550's laying around I was thinking of putting one in my intercooler piping with an AIC like the HKS III or the Haltech F5 with the injector set to open at 9 psi and above, maybe that way I can turn my 720's down and not work them as hard.

So instead of getting rid of the stock 550's and adding two 720's, keep the 550's and add one 550 to the intercooler piping.

1. 4x720's = 2880cc of fuel
2. 2x550's + 2x720's plus 1x550 with an AIC= 3090

Which would work for my setup? Or am I making this harder than it should be?

 

with 2 720's and a walbro I think you should be fine at 12psi at 0%... I don't know why you are up to 25%

 

Well thats what the wideband is telling me. Anything more than 11psi of boost will be borderline for the injectors that I'm running. I already have the injectors turned up but I don't want to run them like that I want to be able to turn them down.