ok, so I was right. the NA has a low and a high, and the TT has a low, medium and high and it works the way I thought it did. haven't been able to find what triggers it to go up to the higher voltages yet, but I'm sure something in the FSM should point that out. I'll look when I get home.

So, you can use pretty much any in-take pump as long as it flows enough.
There was an old Option magazine that said the stock NA pump flows at 195 lph. (don't know if that is 100% accurate or not, but it sounds about right) The walboro flows 255lp, but at like 35 ish PSI. The stock TT pump flows 255LP but at 50 psi. The NA pump has been known to handle up to 400 hp. The walboro has claims pushing 500. and the TT pump has claims at 700 hp.
So, for my simple, my fuel pump is dying, what do I do problem, a Walboro will do just fine. Because the FPCM runs the pump at a lower voltage, it doesn't whine as bad when you are going slow enough to hear it. Many Z32 owners have claimed that they can't hear the pump. I figure that's just because there is too much wind and road noise by the time the voltage gets kicked up to make it really whine.

I'm going to get my hands on one and see how it goes and post it up.

as for the answers to my other "hhmmmmm... I wonder.." questions. No answers yet. Still more research/info needed.