having owned a convertible years ago, and now having a boxster - I consider the stereo in a drop top to be low priority. when the top is down I'd rather listen to the car, and given the wind noise - you can't really enjoy a $$ stereo anyway. when the top is up there is still a fair amount of noise intruding into the car, making it not really conduvice to having an "audiophile" system.
my daily driver is much quieter and I have a nice system to enjoy in that car. if the boxser WAS my daily driver, and I spent substantial top up/commuting time behind the wheel, then I might spend money to upgrade the system - but I still think i'd avoid going nuts
in my opinion - the best music this car makes comes from the motor.
everything else is just static....