What is generally the fastest bravo style lower on a 85mph boat??? I know the Imco SCX lower usually cost a couple MPH.

I don’t think there’s anything to be had at that speed over the stock lower.

Ok so what’s the strongest bravo style drive that won’t scrub speed??

SCX with the dual down shaft lower I’d say

The Imco SC is faster than a bravo, but the skeg isn't as long

lookin for something behind turbines again??

From test results that I've seen, Imco SC has generally been the fastest by 1-2mph. It still uses XR gears though and not really any stronger.