I have listened to the meridia upgrade system as part of my test drive and was particularly impressed for a manufacturer supplied piece of kit, especially compared to my current system.
Now my current system is a 3 way active pioneer PRS system up front supported by a 10inch orion sub. So is not bad
What type of problem are you encountering i.e. error in soundstage (too high, too low, drawn into the centre of the car rather than in front) or a problem in the quality of the sound i.e. too thin or too heavy on bass etc?