injectors and head
 

hey yall, i looked all over miata.net and couldn't find anything, so i figure i'd post here...
are the NB injectors (these are all-blue, not just diff colored tops) compatible with the NAs? i've heard they were, and heard they weren't due to impedance.
just trying to find a straight answer.
and is there a way to tell if a head is an NA 1.8 or an NB 1.8? how?
thanks!

Yes they work.

Different bore spacing.

for the head, i was looking more for like markings or codes? so i can tell if i'm buying an NB or an NA head by just looking at it.
i know the plugs are diff on the injectors, so i guess i'd need those, but will my NA be able to handle them? not using resistor boxes or anything like that.

94-97 plain jane head BP05
99-00 & 04-05MS head BP4W
01-05 VVT head BP6D

thank you!