Front Coil Spacers

Hey all my suspension sagged a little in the front due to a winch, so I decided to put 15mm coil spacers in and had airbags installed in the back for towing. Very happy with how it sits now, though since they have been installed a knocking noise is happening when going over bumps and sometimes when turning left or right and especially when its driven in wet weather..Its quite loud and is very annoying.. My mate took it for a drive and said its definetly the coil spacers as the coils are not seated properly as they were before the coil spacers went in..
Does this sound right? if it is I am thinking of going to Dobinsons and getting front springs made to the right height so I can do away with the coil spacers.
Any thoughts?

Cheers
Dan