You mean the HKS F-con V pro....this is a full stand alone engine management computer, HKS also do a F-con IS. The F-con IS is a Piggy back type computer which manages fuel/air flo and timing...similar to Greddy Emanage ultimate,
Both of these are far more superior to the Apexi SAFC however finding a tuner for these HKS computers is a bit of a bitch.
HKS do not sell there software for these computers to the public.
To obtain the software you have to complete like a 4 year tuning school at HKS america or Japan. once complete you are then able to use the software. Hence the very rare amount of tuners availiable for HKS comps outside of Japan.
How do i know this???? because i run a HKS F-con V pro in my Nissan Cefiro, and everytime i need a tune or do a mod that needs tuned in after fitting i must send my car to sydney at BD4's (licenced HKS dealer here in Aus) for a dyno tune.
The F-con is a great computer with a larger MAP resolution than most aftermarket computers such as APEXI's power FC (PFC is a piggyback). HKS offer a 32X32 MAP resolution where i beleive APEXI pFC is at 16X16 MAP resolution. I beleive the APEXI PFC comes with a pre existing MAP so its basically or very close to plug and play.
The F-con MAP from factory is blank, so it needs to be tuned before driving.
Having said that, The APEXI power FC is still a great computer.
If your looking to run a piggy back type computer on your car check with your local tuners as im not too sure about the abilities of tuners in the UK and what computers they like to use.