Seastar from Teleflex Marine I think is generally accepted as the one to use for outboards.
They have a handy website here which helps you decide which is the appropriate system for your application.
Be carefull which helm unit you order. Otherwise you could end up with 6 turns lock to lock which is a nightmare. Remember most good cars are 2 or 3 turns.
Baystar for a 90 will be fine, you can upgrade the helm to give you less turns lock to lock however the 5.5 I had on my last RIB wasn'tso bad and my children could operate the steering as well.
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Andy
Looks Slow but is Fast
Member of the ebay Blue RIB cover club.