I’d avoid the mirage and even the later plus version. Had their day and their place once upon a time…but certainly, there is better and much smarter props around since.
You’ll know plenty already about props AD, I’m sure…but need to be careful where you go from here. It might help to tell you that I know that generally the rev4 of any pitch..will act like at least another inch of pitch, than other props of the same pitch. I know of a number of examples personally that absolutely do. Same for the tempest plus 3 blade. Which is the 3 blade version of the rev4 or near as damn it. Also acts like another inch..speaking in terms of rpms from way down low all the way up. So if you are a little under propped with say a 19” rev4 or tempest plus…and go to a 19” of most any other prop from merc I know of…you’ll be further still under propped again. I’ve a 19” tempest plus I use most times. It will 100% show lower rpm at speeds from displacement up to almost 2/3 throttle, when compared to the 20” enertia (not eco) I also use. Then to absolutely emphasise my point..jeez…compared to the likes of a laser 2 of 19”…there are hundreds of rpm difference anywhere in the rpm.
I love the tempest 3 blade. Very little slip and despite acting like a little more pitch for rpm…somehow doesn’t act like more pitch for getting on plane. Will plane just as quick or quicker than any other prop around that pitch I’ve tried out. Big blades that are handy on a rig like yours. Takes loads of trim and keeps holding on. Will certainly see less slip than the rev4 at the top end too. But just depends on how much more you have to go (if the limiter wasn’t getting in the way). If you are only just nudging it occasionally, then a 19” tempest might just bring it a hair below that, having less slip). But if you’re hitting it easy, all day any day you open the throttles..and not lacking on getting out the hole…take her up an inch or so I’d say. Up to you…but I’d ditch the mirage idea. Know of a few of them on scarabs and formulas. Not impressed and they all slip a fair bit top end, that I’ve known. Heavy big buggers to get turning too. I’d be trying out some tempests or enertia/enertia eco’s out. Don’t know personally of any boats with the eco on them here. Can’t speak highly enough of the normal enertia though. Would they suit your boat though ?? I don’t know. Very light things and thin blades. Lightning quick as a result. The bravo 4 blade might be worth a try too. These are the best of the 4 blades that I’ve seen for sure. But again…suitable for you ?? Who knows. For a 4 blade…fairly good for slip top end. For a 4 blade…I’ll emphasise! Keen to hear how you go. But thought I’d make you aware of the anomaly around the behaviour of the rev4 and tempest, in terms of being careful if the thinking might have been that you can use their data and figures as a reference when working out what prop to get next. They don’t tend to play the usual game at all. Definitely behave like an inch more…as a given.