Roger,
The crossover is designed for a specific drive unit and it is the combined response of both the driver and the crossover which determines the actual output level. If your new driver is 10dB higher at a certain frequency than your old one, the resulting output will also be 10dB higher.
Tim

RoPieee Allo DigiOne Signature, 561, DSP5000, DSP33, SW1600, M3.
HH1 Number 48