The big difference is the GTECII runs more ignition advance than the other chips thats why you need to use a 97/98 ron fuel to prevent pinking. There is no need for a front mount intercooler because it runs the same boost as the GTECI chip.
You will notice better performance off boost and a better mid range punch.
Its probably more suited to a tuned car but so long as you use the correct fuel you should be fine.