If you want a carb and keep the aux. ports it would have to be DCOE not a Holley. and this would probably be an overall better set-up than the holley, but the holley looks like it would be cheaper for you though.
DCOE http://www.mazdatrix.com/r-weber.htm
Holley http://www.mazdatrix.com/r-holley.htm

 

I think it's an upper manifold that RB sells to mate up with the stock lower manifold IIRC.

Whatever posessed you to bring back this old thread is a mystery to me.

 

YEAH! Why the hell do you people do that???

 

holy thread resurrection batman!!!

 

because im considering putting a 13b on my car, why make a new thread and get all these posts again when half hte answers are here, and the other half are on the way