If you are just sticking a plug and play chip, then I would only fit an uprated regulator, IF you have an uprated fuel pump AND access to a wide band lambda to check the fuelling.
Even then ,it should only be fitted if you have documented fuelling problems.
Still this is very crude, and you will increase fuelling slightly across the whole rev range, at idle, part load etc etc , so is not ideal.
An uprated FPR can be used, of course with a custom ECU, mappable UCU, to wring a tiny bit more out of the injectors, but its hard to know how used OE injectors will respond, and again you will be increasing the fuelling at other parts of the Maps that say a piggyback ECU doesnt deal with ,say the Unichip for example, doesnt compensate the idle map.
When I spoke to Paul, he suggested, that at most you might get an extra 5% out of the injectors, really I think this is the most appropraite time to fit uprated regualtors.
The trouble is , a lot of peepes read these threads, and end up bunging on uprated regulators, in inappropraite situations ,just because 'everyone else has done it', and then never get things checked professionally ,and then wonder why their engine either breaks or loses power later on
Joe