Fuel Pressure should NEVER be adjusted for OTS software IMO. In fact, I rarely advocate the use of higher pressure as it strains more things than it fixes, even down to alternators and relays. If you want more fuel, put bigger fuel injectors in it. Simple.

I dont see any reason for you to be unable to set fuel pressure to standard and just run her as a totally std 1.6i FRST Melvin.