The installation actually went pretty smoothly. The thing that gave me the most hassle was running the wiring from the cabin to the front doors. Other than that it was pretty straight forward! The Infinity speakers do sound amazing for mids and highs, though the highs are a little too harsh for me personally. Though, I've owned four other sets of Infinity speakers in my lifetime so I know that over time the mids will catch up to the highs and they'll sound better all around. I just can't wait for that to happen, these three ways are very bright. (not that it's necessarily a bad thing.) I ended up disconnecting the factory tweeters in the A pillar because it did not sound as good with them connected. They sounded very cheap and crappy after getting the Infinities in there. I left the center channel hooked up, but very quiet. One thing I really strived for in this installation VS previous installations is that anything that is factory is very precious. I did not want to disturb ANYTHING unless I absolutely had to and I was mostly successful in that aspect. The only factory wiring I had to cut/modifiy were the four speaker wires from the BOSE amp going to the rear speakers. I only had to cut them to get the full range signal from the amp, and so that I could externally amplify the rear speakers. The front speakers are powered by new cabling so the factory wiring did NOT have to be touched for the front channels. I ensured to solder all of my connections so anything coming loose is out of the question, it just simply is not going to happen.
here are the front stock BOSE speakers along side the new Infinity replacements..
One thing that really impressed me about the CTS is that there aren't any wire harnesses that have to be disconnected from the door panels when the panels are being removed. I was very surprised about that. It's apparent that GM really is getting into their whole "dock and lock" technology.
Backside of Rear door panel:
Rear BOSE VS Infinity:
One thing that I like to pat myself on the back for, was the use of the original harness for the front BOSE speakers, on the rear speakers so that cutting the factory wiring would not be necessary. The terminal connectors fit PERFECTLY on the new Infinity speakers. The connectors to the door panel wire harness is also the same as the front speakers'. So not only did I recycle a factory part, I can also move it back to the front speakers should I ever want to sell the vehicle.
There was also one small problem with the mounting of the 5.25" infinity coaxials on the rear door panels. There was a 1/4" gap between the speaker mount,and the door panel. The easiest and best way I could find to fix this was to use the Infinity speaker grille insert between the speaker, and the factory mount. I used rubber stripping between the speaker grille, and the door panel mount to make sure it was air tight. It worked very well and seals perfectly.
Other than that I have the Front Kappa's outboard tweeter glued/tied to the factory harness near the speaker spacer on the front doors. They fit pretty perfectly.
This is the new JBL 4 channel amp. it provides 150 Watts Per channel. @ 2 OHMS.
I ran out of time so I wasn't able to mount it or clean up the wiring. It works for now though! Other than that I think that's about it. Any questions from anyone?
In Summary, the 2007 Model Kappa speakers sound pretty good, though more harsh than I remember past years' speakers. They sound very close to what my Kappa Perfects sounded like in My Aurora though. I can tell you for a fact though that this 6 speaker system absolutely blows away the factory 8 speaker system completely out of the water. The BOSE speakers sound absolutely horrible in comparison. It's surprising because you really don't notice it after you get used to them!
at the very least IMO you should make a small ramp for it to sit on that will press against the back seats. and just get some carpet to match the stock trunk color. 
