I would have a GOOD drive guy go thru the drive.
If the gears are stock, have him put in the HD 1.50 gear set, and set up clearances carefully.
You can get rid of that wing plate by adding a touch of cup to the prop to help with getting on plane. Change drive oil every 10 hrs., and add a simrek drive shower, be sure to tell them it's an SS. Properly taken care of, these drives are not as weak as people think!
See pic to the left....

Hard to tell from the picture but is that a "Mirage" prop? If so, a Mirage Plus may help you getting on plane. The Mirage Plus has added cup to the prop tips. Helps getting on plane and carrys the bow a little better.

Fixx
 

I dont know it this would apply to your boat but the hydromotive OT 4 blade which is a out board prop works the best on a alpha SS drive..But thease props are being used on a 16' and 18' donzi classics with ss drives..

may want to do a search on donzi.net or inquire about it,theirs allot of info at this site on your boat,from what i read its not the fastest hull so you might just be pissing in the wind on props..

I had Mirage plus and it was still very hard to get on plane. I had the diameter brought down to 20.2 and just a little more cup added, it made a huge difference, boat planes faster, and mid range cruise is excellent. It's no rocketship but for the way I use the boat it works for me. Best top speed has been 65 with the current props.

The prop is a Mirage 23p. I found the numbers 86K112 on the lower, looks like there were 2 other digits in front of the 86 but I can't make the out. I think the the 86 is the year but I don't know what the K112 stands for. Anyone know?