That is the reason we don't paint our kits. We can easily color match to the factory paint codes in our paint shop here, but like FocusOnThis said, weathering can change this.
Also in reply to 02focuszx3, for our kits (don't know about other manufacturers) its a fairly easy install. Old bumper off, new bumper on. Everything is molded off of factory parts, so everythign fits and lines up perfectly. If you can take your bumper off, you can install one of our kits.
So back on topic, I recommend unpainted kits, then painting after install to color match. If you have seen a slightly weathered car with a new painted kit on it you would agree. Its so slight, but still so noticeable.
OT: FocusOnThis, would either of your civics happen to have a sticker on the back window that says "Focus On This" ??? I keep seeing one parked in front of my apt.