As we are benefitted by MOSFET's higher input impedance ,while analysing the small signal model,the effective input impedance gets reduced because of the biasing resistor which is connected in parallel in the order of some low kΩ's.But that resistor is needed for effective biasing.
While bootstrapping the external resistor connection you make will stabilise the operating point but it will be open in the small signal model thus having no reducing effect on our deice's input impedance.
If you are more specific with your circuit, then I'll clear you efficiently.