Sorry to revive an old thread but I thought it would be good to have my information as part of this existing thread rather than a new one.
I found a good deal on a 2012 DF90A and took the plunge. Here is a bit of info that others considering installing the same motor might find useful.
Thank you Victor and everyone else for all the info you provided in this thread. Additional thanks to Victor for responding to my questions via PM. It took all the guess work out of installing a DF90A on my 26X.
If you install the engine interface cable to get engine info on your chart plotter be sure to get one with a software version that is not 2.7. Version 2.7 has a known bug with fuel flow measurement. Full info on how to get it working can be found here:
http://www.thehulltruth.com/marine-elec ... ne-13.html
As mentioned in previous threads the Analogue tach is not perfect.
Our tach shows correct RPM compared to interface at idle (700 rpm). When tach shows 2000 RPM interface is 2050. When tach shows 6100 RPM interface shows 6300.
My prop is the Suzuki 14 inch blades * 13 pitch that came with the motor (had to ask for it as they would have included a prop more suited for a lighter boat by default).
My boat has bottom paint.
6 Degree transom wedges.
Just finished breaking the motor in and put in to do a long weekend trip (loaded for bear) and did a speed run to see if we were propped right.
Weight wise we had the following:
Empty ballast.
Myself (225 pounds), my wife (???), my 12 year old daughter and her friend (115 pounds each).
50 litres of gas (12 Gallons)
55 Litres of water on board in a bladder hooked up to pressurized water system.
Mast was up. 1 anchor with 20 feet of chain and 150 feet of rode.
A large cooler full of ice, water and pop. Food for the weekend. Two crab traps and all gear for them. Two fishing rods and tackle. Full kitchen (wallace stove\heater with 4 gallons of fuel, smaller gas burner, small rail mounted BBQ with 4 1 pound propane tanks, tons of cutlery, plates, bowles etc). 4 sleeping bags and pillows.
Full enclosure. Swim deck over steering linkage.
Conditions were: slight chop and slight wind on the nose.
Max speed was 23 MPH at 5300 RPM.
The kids were on the bow and we stayed dry in the cockpit, the spray was mid-ship.
I was a bit worried we were over propped.
On the return trip all the same as above but with ballast in:
Conditions were flat and no wind.
Max speed was 20.5 MPH at 5100 RPM.
I was surprised our speed was so close to unballasted. The kids were on the bow and the spray was much worse, towards the front of the boat, and spray was getting into the cockpit. Friends traveling with us took some pictures and we were definitely bow heavy with the kids up front and ballast in.
Since I was a bit worried that the boat was over propped I decided to try a speed run the next day at a local lake with the boat as light as possible (Wake board configuration).
What was on the boat:
Anchor with chain and rode, mandatory safety gear such as flares etc, 5 Gallons of fuel.
The mast was off (not just down, it was left on the lawn at home). I was the only one on board.
So it was basically stock with the mast off.
Max speed was 32 MPH at 6300 RPM. Conditions were pretty much flat with just a hint of wind. Just barely made 6300 RPM and only in one direction. The other direction was 6200 RPM at 30.5 to 31 MPH.
Best speed was with motor tilted up slightly (trim gauge showed 25%). Trimmed all the way down I lost 2 MPH. Adjusting trim did not impact boat angle much if any. Given that I am not sure the Transom wedges are needed on my boat but figured it was better to have them just in case.
Given all the above I am pretty happy with the prop and the engine is performing pretty much exactly as I had hoped. It is actually fast than I though it would be in the mast off configuration. When I plugged my numbers into the prop calculator here:
http://www.mercuryracing.com/propellers ... ulator.php
I was expecting a top speed of no more than 28 MPH with the 13 pitch prop.
The Suzuki prop must actually be more than 13 pitch or have cup or other characteristics that make it faster than its calculated max because when I put my actual numbers in I have prop slip of negative 5.
Prop pitch = 13
Gear Ration = 2.59
Engine RPM = 6300
Actual Speed = 31.4 (I hit 32 but it was only one direction, I was able to sustain 31.4)
Calculated slip = -5
Here is the summary:
Wake board configuration: 31.4 MPH at 6300 RPM
Loaded for bear, no ballast: 23 MPH at 5300 RPM
Loaded for bear, with ballast: 20 MPH at 5100 RPM
, but some day I'll catch a good weather and test it with 2 onboard, it should look a little better.
the experience is far from it, I could not let the throttle down even a little without noticeable speed change. May be the sea condition was the factor, but I am leaning towards the common opinion here that the 
