I'm not sure to be honest...it has a D15B2 in it right now...it has already had one swap prior to me owning it...I believe it is MPFI...
The D15B2, according to a spec sheet that I have is the following...
1.5 16V, SOHC, PGM-FI 1493 92HP@6000RPM 88-91 DX/LX (USA)
The D16A6 which comes stock in an Si is:
1.6 16V, SOHC, PGM-FI 1590 108HP@6000RPM 88-91 Si/CRX Si

All 90 Civics were manufactured at the plant in Allison, Ontario...mine rolled out in August of 1990. So I assume that an Si would be an Si...but I could be wrong.

Can anyone clarify?

Jason.

Here's the link to the engine's that I'm looking at in Montreal...

http://www.naganojapanese.com/shop_online_honda.html