Kappa components are really nice. You made a good choice.

What amp are you using? What are you expecting out of this system?

I am slowing finding out that rears (mid-range, mid-bass, subs...) can put the whole sound system out of phase. I blew some Infinity Reference 6x9's a while ago, and finally decided to replace them with something. I have/had Reference 6.5" coaxials in front, which sounded pretty nice, but thought I needed something extra to fill the rear... maybe a little extra bass. I decided to build two little boxes to fit behind the cladding, and bought some 6.5" Vifa glass fiber cone mids (high-end home audio drivers) for them. After installing them in the back, I don't fell like it helps the audio much at all, if at all.

THIS article about absolute phasing is a good ready, and makes a good point.

I have the Vifa's in, and swapped out my Infinity Reference in the front with some Crystal coaxials, just to try something new... and I think I like the Infinity's better. I'm thinking of buying some components and seeing if I like placing the tweeter in the stock position, and maybe even getting rid of the rears all together.

We'll see.. good luck!