if you have one of those old freon recharge cans laying around with a gauge on them you can use that as a fuel pressure test gauge, it normally fits right on the valve
chances are the pressure is fine. But I would say bumping up the adjustable pressure regulator a small amount might get you better mileage. For the metro there are a lot of threads over on teamswift.net showing how to tune the fuel pressure regulator. I think just adding a shim to it would increase the pressure but I haven't really tried it so I can't say for sure. The reason is the computer is probably near it's upper limit on adding fuel so increasing the pressure makes the injector flow more and gets you back near proper tune.
Really without detailed instrumentation there is no good way to know exactly what is going on. But the kicker is even on my van with the computer retuned with a wideband O2 to run on E10 it didn't gain much in mileage over the stock tune. but it did run a bit smoother.