From n54 tech:
"We've started development on ISO firmware for the N55 Stage2 (JB4). It offers smoother and more consistent boost control, further reduced lag, and sets up the N55 JB4 to control larger turbos and the BMS N55 flash down the line. All in all good stuff."
JB4 G5 ISO, E85 BB FLASH, WALBRO 455, DP'S, AMS FMIC, AE EXHAUST, VRSF CHARGEPIPE, SYNAPSE BOV, DCi