I can never figure out why you guys do these things to yourselves.
Look, 1000 horsepower is equivalent to roughly 2.6 billion joules of energy per hour. A gallon (3.8 liters) of gasoline contains about 132 million joules of energy, therefore, a 1000-hp crank horsepower engine has to be able to burn just over 76 liters of gasoline per hour.
However, turbocharged gasoline engines are only about 1/3 efficient (don't feel bad, NA's are even worse) and two thirds of your energy escapes as heat rather than as power to the wheels.
So the engine actually has to be able to burn at least 228 liters per hour, which is well within the spec of a Walbro 255 liter per hour pump.
Add in a 30% margin of safety (and that's a huge margin) and call a single Walbro good for 700 at the wheels.
I've seen quite a few Supras (both MKIII & MKIV) make over 700 at the wheels with a single Walbro pump, but I do feel it's pushing it.
Adding a second pump doesn't have to be expensive or complicated.
The simplest method is to simply strap the new pump right next to the old one and hold them together with a large (4" or so) hose clamp (you can pick these up at Home Depot, etc).
Next drill a hole in your FP lid, put a bulkhead fitting on it. Connect the pump to the fitting on the inside. Run a new set of wires for the new pump, seal the holes. Drop the whole thing in the tank and run your fuel lines.
This is simple, cheap, supplies far more fuel than you are likely to ever use, is 100% dead quiet and minimizes the amperage draw on your electrical system.
The Walbro pumps are almost twice as efficient when it comes to current draw when compared to the stock MKIII or MKIV pump. I've never looked at what the Aeromotive draws, but I doubt it's anywhere near as efficient as the Walbros.
Just my .$02 - ymmv.
