What else could be the issue? I am doubtful of it being the coupler because I have no bruning smell ever and I had the Bravo 22 issue three years ago and went back to the 21p with no issues and no the 21p plus is acting the same as the Bravo 22. It acts just like if you had the drive trimmed up and tried to go on plane where it would initiall bite and then spin up to high RPMs. I would think possibly too much stern lift but that seems crazy because the drive is well below the lowest part of the transom. Very aggrivating. I will say when the 21p Plus did finally hook up the boat cruised very nicely, but I need the slow grip for those rough days where I cant be doing 45mph.

I think you should inspect the drive and prop on land, is the hub ok?

Everything appears to be good. No play in drive. Splines are squared on the ends not pointed on the shaft and coupler. Drive lube changed every season and when coming out never a burned smell or lack of fluid. Plastic hub is new and no spinning in the prop. Anythig else to check?

Thoughts on this......I had a guy at work ask me if I had a drive shower (which I do, the solid double tube) and he is swearing that the tips below the cavitation plate are causing the blow out. Anyone ever heard of this and could this be true. I will say the blades on the test props have been longer than the ones on my original. The thought process is that the initial water trying to push into the pickups and pushing water back into the tips of the prop causing the blow out?

Thoughts on the drive shower?

which side is it mounted on?

I think you answered your question...get a new solid hub 21" Mirage Plus.

It is a dual pickup mounted on both sides of the drive.