which is the better of the two? I need an EMS before I do my fuel system just wanted an opinion on which I should go for.

 

Ive heard that HKS F-con doesnt work on S4's im not sure why though (maby its just nobody does it.)

also I belive the F-con is a full stand-alone and you are comparing it to SAFC-II which is a piggy-back and profec B which is a boost controller.

ive never heard of anyone using AEM EMS on a S4 though. Im not sure exactly what u are looking for wheter it be a piggy back, full stand alone or a boost contoller.

 

If your looking for stand alone ecu wolf 3-d, or haltech e6k,e6x, e11

the hks F-con is good if you get the f-con V pro I haven't seen that here much but used a lot in japan but expensive. Now if you want plug and play (kind of) try an Apex-i PFC. ranzo used on in his fc. in all cases your looking at $1300 about.

the F-con is more like 1700.

if you want to go cheap apex safc and a bigger maf.

 

safc if your just want to be able to control some bigger injectors (=able to push more boost)



I personally like my wolf 3d for a stand alone, but I don't have a lot of experience with the haltech.



even the safc is a powerfull unit so make sure you dyno tune before hammering on her

 

Alright, Well thanks for the info I think I'll go with the f-con Vpro, I have the cash for it

 

Big mistake if you live outside Japan, and still a mistake if you live in Japan. A power FC, Wolf 3D, Haltech, or Microtech are most likely your best choices, and can do what the Fcon can do, and can be tuned by anyone, and cost less.