Seems odd... I've done several of these with no squeaks or issues at all.
Did you throw away the old bolts and clips and use new bolts? Are they torqued properly? Did you do the firm and torque with the car on the ground i.e. leave it loose, then tighten it all with the bar in the down position?
Any change you have something else broken? An axle mount or bushing, or the inner sway bar?
Very bad idea to put compliant material between axle and ARB as it will create a leverage moment around the bolts and overstress them and they may snap. If it's squeeking the problem is elsewhere - likley the now stronger spring rate is stressing other suspension components.