How different will a 4 lbs. 2" memory foam topper feel INSIDE a mattress? I would like to try putting it inside my quilted zipper-top mattress just to see if it gives it a cushier feel. Where would you suggest placing it within the layers? On top? Sandwiched between a firm PU base and a 32 or 44 ILD later layer? This would be over coils.

Thanks in advance for any suggestions!