The Civic GX was introduced back in 98. It's not very popular in the cold states where subzero temps are the norm for nearly a month straight.
I tried to buy one through a dealership in 2001, but was informed that the GX performed very poorly in MN. Poorly as in it had running issues and line freezes, so it was not offered here anymore.
I know for sure that the 98-00 variant was identical to the other motors available with respect to the injectors being different.
Side Note:
The pistons from the GX (deemed "PMS") can be used in the D15Z1 (VX) motor along with a D16Z6 (Si) head to create a 1.5L motor that makes nearly 140HP at the crank (14 more HP than the Si model D16Z6 of the same generation).