[Rob]

Is your amp 600 watts RMS or 600 peak?? If it's 600 watts peak, then it may only really be putting out 300 RMS...and true, unless you have the Excelon series Kenwood amp, your amp isn't the best of quality.

Also, you're probably running less power to 2 12's then you're buddy is to 2 10's which is also a factor in the difference in sound between your system and his....

One finally note, the Kicker Solarbarics have a higher SPL than the MTXs do (I think). SPL in a nut shell is the speaker's ability to perform based on the amount of wattage you feed it. The higher the SPL, the better.