You'll eat your words when you try to row that boat...
9.9 vs a 20hp is gonna totally change the way that thing rows, sits in water and tracks for plugging, and not in a good way...not to mention the heavy ass will make it try to get ahead of you on the corners, just like car.

Not to mention that drift boat hulls aren't meant to plane, so you'll be making the engine work harder than it needs to withought any real difference. I also doubt you'd get a good alignment with your hull to your intake to make it worthwhile as well.

The final nail is that a 20hp jet isn't going to do dick for pushing a loaded drift boat many places that you'd want it to, you'd need at least a 30 and then we get back to a problem of too much weight and again the hull issue on plane

Do yourself a favor, get another 9.9, a good prop gaurd and get back after it