Lowering Springs?

Never heard of them, if you are looking for cheap springs, most guys seem to like the FRPP letter series springs. If you want well built stuff I'd recommend H&R. I'm running them with Bilstein dampers on my 91 and I am really happy with their performance.
 
JDM: Japanese domestic market.... probably not the place to start looking for mustang parts

+1

JDM is the biggest fad to hit the ricer world since 5' wings and NOS stickers. Complete garbage.

Look into Eibach, STEEDA, FRPP, and H&R for mustang lowering springs. For reference, I have H&R Super Sport springs on my car (see sig).