I work at a very popular parts store and this is what I found:

(My research is based upon my 1993 1.6 injectors and harness)

beck arnley number :
155-0154 are 550cc (purple top)
155-0121 are 460cc (red top)

There are similar numbers that have different harness connectors for Rx7's so you must be careful. These are the only two I found that fit the miata connectors.

Can someone please confirm this info?

 

Those are indeed correct beck arnley part numbers for rx7 injectors that fit. There are other injectors that fit though...read the FAQ for a large list.