for the time being, i decided to keep my factory tape deck in my car but i switched the rear speakers out with some MTX 6x9'*.
anyhow my question is...the higher the volume = lesser bass? i have noticed im not getting half the sound from these MTX'* that i did than when i had them in my Nissan truck(had a kenwood cd player installed 50x4Watts). Is the factory deck causing the bass to drop to a lower level when the volume is higher? either its a factory safety precaution so you wont blow the speakers, or i have a wire crossed.
Cause when the volume level is low i hear and feel much more bass than when it is turned up....

I've seen some of the stock units act this way. You could either get a better stock unit or install an additional amplifier.