2520 trim tab setup

[slacka]

I've read all the write ups and ideally 24x9is the size I'd want. But as luck has it I got my hands on a complete used Bennett hydraulic tab system For $250. But the plates are 18x12 .... Is it gonna make that much of a difference that I should start looking for 24x9 plates or can I run what I got and not lose to much? Is there a major down side to running 18x12 .... my old boat didn't have tabs so this is all new to me .thanks