I found this link while searching for my problem with the car running lean since going BPU, I suspected the HKS FCD and this seems to back up this up.
I can't find greddy BCC's available as it seems discontinued according to GReddy, is there another product that does the same think without getting a piggyback ECU.
n.b. I've taken the car to a rolling road who confirmed it is running lean, I've replaced the fuel pump with a walbro when going bpu. AFR reading is around 12.2 with WOT.