Installed a Walbro 255lph pump this morning...
I went by and got a GSS342 from Dallas Mustang for $89.99 and installed it this morning. It is the same pump for the 96-98 Cobra's.
I think that it is a direct bolt in for 94-97 miata's, on the 89-93, there are a couple of options. The pump is 1/4" taller then the stock pump, so you can either get the kit from Jackson Racing that has a shim to lower the base upon which the fuel pump sits, or you can get the dremmel out.
I chose the dremel. The fuel pump inserts into a cone type recepticle (kind of like the funnel on a refueling aircraft.) You can cut the funnel off and use some high pressure fuel line (1/4" I believe) and secure the pump to the freshly cut hard fuel line with clamps (mine came in the mustang kit...)
It was about an hour job, and now I dont have to worry about the 14 year old fuel pump having to work so hard for the turbo.
It is such a strange concept for me that the poitive and negative wires are submerged in fuel....I would have never tried this....
Now I just need a wideband and some time.....
Chris