Adjustable Fuel Pressure Regulator, Good or Bad??

[CoronaST170]

Hi everyone, I am new to ToyotaNation, My name is Marc and I own a Toyota Corona St170 88 1800cc engine. The engine is TBI - Throttle Body Injection.
I am pretty tempted to go out and buy a fuel pressure regulator to replace the factory one. I have a Cold air box and a muffler and want to know if its a good idea?
I am wanting to get more power and acceleration and make the engine bay look good by adding a new toy under the hood.

If I do install one will I need to change the ignition timing?
If I adjust the pressure "above factory" so more fuel is been dumped will it run rich.
Pro's and Con's

Any help and advice would be much appreciated

Marc