I've heard of this issue, make sure the injector is pushed down into the manifold before you install the fuel rail.

I know this is a bit late for you Pusha, but we do offer a 100% drop-in fitment injector for Miatas. No cut/splicing needed, your stock harness will plug into our injectors.

They do look just like the ID injectors. I had to cut off the black plastic grommet/bushing down at the bottom/tip of the injector in order for it to fit in the head. Also, I used the flat-ish rubber bottom bushing instead of the o-rings provided. Works 100%.

I wonder why they don't look like the pics in the link?

Because the tips fit in the head, all I have to do is bore out the little OEM plastic grommet thing to fit my injector tip sans o-ring?

I eventually purchased injectors larger than those I originally was looking at.

If the OEM seal fits in that spot replace the o-ring with it. It be a perfect fit, just do it nigga.

dude that isnt the injector you linked us initialy the top portion looks to short and overall the whole unit is shorter. Im surprised you didnt compare the pic and what you got and call BS on the company for sending something different.
http://www.sprayitracing.com/Lucas.jpg is much different

...

I bought these:

http://www.sprayitracing.com/52lb%20...0Impedance.htm

http://www.sprayitracing.com/52lb-Bosch.jpg

I got those for the same cost as the smaller ones, but from the looks of it, neither would simply pop in.

So I reamed out the cushions and slid them over the male end of the injectors. Hopefully this'll work...