i am not sure why you are choosing the st12 sport tabs. They are dual actuator trim tabs usually used on higher performance boats. The standard 12 x 12 or m120 will be just fine, cost less and take less time to install. But some folks like the black powder coat on the st12 and if this is why you want them, i can understand that, they look great!
Like all things, the best thing is to measure twice (or three times) so you only have to drill holes in the transom once!
If you go to our website
bennett marine: The world leader in trim tab innovation, quality and service you can find the installation instructions for all of our kits. Also here is a link to a video
bennett trim tabs video player that shows the installation of the m80/120s, but the general aspects pertain to all of our kits.
Look them over and let me know what questions you might have.
