Hi Brett
Sorry to hear about your fitting issues. I guess I took the easy way out by getting Seafarer (Lindsay Fry) to recommend the most suitable units and then stick them on.
Re your cavitation, I found that even when my tabs are fully up they have the ability to lift the rear of the boat higher in the water when cruising etc. It may just be that you had your motor was set at the ideal height before the tabs were fitted and you may now need to go down one hole. Thoughts?
Cheers
Chimo