FWIW, after some research, I ordered the SX- 15404 regulator.  SX regulators
seem to be the universal choice of the RX-7 aftermarket folks, and it does
appear to be a fine unit.  Here's a site where I ordered mine from.  I've never
ordered anything from them before, but they have a good description of the
regulator.  

http://www.turboimports.com/sxboosdepfue.html

Cheers,
Rusty
> Im in the same boat, not using the stock regulator and
> don't know much about the aftermarkets. Does anyone
> have a specific suggestion?  Thanks Jim Coffman