I just got my 99 civic sedan on saturday but so far i've got the following installed:

JVC KD-XHS855 headunit
Digital Designs C4 amp
Pioneer TS-D691S rear fill

Looking at possibly getting a set of JBL 608GTi splits since i can get a fairly decent price on these. I was also planning on getting JBL W12GTi sub as well.

If anyone has had any experience with these products, any info would be great!!