That is a nice setup. When upgrading speakers look at the ohms. The infinity speakers are 2 ohms and the Focals are 4 ohms as I will be adding two more speakers soon. So if you wanted to add more speakers ,depending on the amp you might not be able to, because it could damage the amp if it is not rated to go below 2 ohms. For more info on this go to. http://www.prestonelectronics.com/audio/Impedance.htm
I understand about impedence however my researh before purchasing found these facts on the speakers. So far they play loud and clear

By the way electronics is my profession for the last 31 years

My source:
http://signature.crutchfield.com/S-BSHMwFj0Iid/s_1086829CF/Infinity-Kappa-682-9cf.html?search=Infinity+Kappa+682.9cf&ssi=0Infinity built the latest Kappa speakers with improved technology and high-end materials to provide you with outstanding sound reproduction. The low-impedance design makes these speakers very efficient, so you'll get great results powering them with a factory or aftermarket stereo. The Kappa 682.9cf 5"x7"/6"x8" speakers feature light, but stiff woven glass-fiber woofer cones that won't flex or distort. The Plus One design offers a larger surface area for improved low-frequency output and efficiency, while longer voice coils produce tighter, snappier bass. Large magnets keep the woofers running cooler by placing more steel close to the voice coils to act as a heat sink.
Infinity uses the same Metal Matrix Diaphragm tweeter found in many of their popular home speakers, so you'll hear the music the way it was recorded with minimal coloration or distortion. The dome tweeters pivot, allowing you to adjust them for better stereo imaging.
The computer-optimized outboard crossover networks employ audiophile-grade components to separate highs and lows, so that the woofer and tweeter work together perfectly. Pre-wired crossovers eliminate a time-consuming step in your installation, and terminals at the end of the crossover wires screw directly to the speakers, leaving no chance for incorrect wiring.
Important Note: These Infinity Kappa speakers use a low impedance design to pull more power safely from your car stereo or amplifier. This design is compatible with virtually all factory and aftermarket stereos.