Hi everyone.
After many hundreds of hours experimenting and learning about XP11, I found some things that I had to do to improve it to the level of some of the other tools that I already have available. I've compiled some of the data, experiences, to share with some pilots I interface with, and decided post it here also.
Some of my findings are listed below, and if someone has some feedback on some improvements, errors etc. post here.

Changes made to C172SP G1000 in XP11 v. 11.11 to improve Cockpit / Forward View, Flight dynamics, Ground handling, and Scenery. XPlane 11.20 does not improve the basic sim beyond 11.11, unless you use VR.

System tested on: 4.3GHz, 16GB RAM, Nvidia 1080GTX, running in 4K mode, and 90.21 Zoom setting.
XP11.20, 42 in. monitor, Logitech Extreme 3D pro, CH Pro pedals, Logitech Headset.

Head / eye / screen positioning, about 24 in away, horizontally, and about 2/3 distance between the top of the instrument panel and top of the screen, to simulate as close to real life positioning.
The instrument panel / inside cockpit forward view, includes, in the example of G1000, the 2 complete instruments and a small portion of the front cowl, and set up using the view point as described below, View point adjustment., to view the wing tips on both sides. I consider that view point to be very important, a requirement, when some one wants to use the sim as a tool to learn / teach, someone how to fly.
All the above motioned points of reference are / can be used to teach and use as reference points in VFR flight.
Some additional things worth mentioning about the present setup and why I decided to stay / use it.
Over the years I have tested, and tried, all kinds of setups, multiple screens, Arduino external interfaces, motion chairs, other Joysticks, Yokes.... and found None to be satisfactory, or add sufficient sensation to the overall feel / sensation of realism, to justify the additional inconvenience, added hassle.
One important joystick assignment that gave me the ability to get away from multiple monitors and be able to get a quick Left / Right view, as needed when doing pattern work, was the assignment of the Twist from the joystick, normally used for rudder control, and use it for Left /Right view. This can be a problem in XP11 since there is no Null zone adjustment, but you can use a way around it see below, Null zone workaround.
I have what I consider better, smoother / more accurate joysticks, but the do not have enough buttons to allow most functions required in a light, complex, GA like A C182RG, without having to use the keyboard..

This tutorial is using the C172 G1000 as a model, but it will improve the scenery and terrain recognition for other aircraft.
Note: Save all the files you may be altering before you do any thing.
XP11, as a basic engine, is an improvement over the previous versions but to be useful as a VFR tool needs some external intervention, to add some of the VFR ground reference points.
The release version has very unnatural looking roads, lacks sufficient resolution to give a credible long distance, accurate mountains, valleys, and other nature references, to a real world pilot.
The good thing about it is that there are additional Addons that are available that can remedy some of those issues, but most of the VFR ground reference points will still be missing.
I found that to satisfy some of my requirements, in the forward from cockpit expected view, and give a good feel or real flight, I ended up having to add a number of things.
1-Photo scenery, using ortho4XP, or download some already available photo scenery, very large files in Zoom 18 that I consider best. Must have Overlays generated also. Used for more real looking roads, mountains... or
2-HD Scenery Mesh v4, if you are Not using Photo scenery, Photo Scenery has it's own mesh.
3-FlywithLua, to correct the water that looks very unnatural, improve clouds, and other issues.
4-WED to create your own missing obstacles, and add some additional VFR ground references.
5-SketchUp to create some of the objects needed.
6-Using Photo scenery with original XP11 road and autogen using transparency.
7-Libraries, simHeaven_VFR-Landmarks, MisterX_Library....

Using the above, and the proper Settings you can get a credible, useful basic scenery sim.

The C172, flight model, was improved but it is still lacking, in ground handling, Xwind, take off, landing, and lack of controller adjustments to give it a good, real life like feel, mainly in the rudder input. Ground handling in Xwind is also a problem that has not been fixed, and it may never be.

The unnecessary smudges on the G1000, reflections in the windshield, dirty window look, and the scary thump noise when it first loads up, are all unnecessary and take away from the actual forward cockpit view and feel of a serious typically clean acft feel as one would expect.

After trying all the above, and still trying to improve the aerodynamics, I find that I may never get to the point where I will keep using it as a primary sim, due the fact that I already have something, that may be older, but it is, in my opinion, a better overall tool.

If you want to se something as an IFR tool, and are using a G1000 in your real life flying, and willing to ignore all the above, this is likely what you need.

View point adjustment.
Cockpit view settings to view L/R wing tips and part of cowl necessary if you want to learn / teach VFR flying.

Start Plane Maker.exe found in your X-Plane11 folder. Select from top menu:

File>Open>Cessna_172SP_G1000.acf>Open Aircraft
Standard>Viewpoint>Long arm pilot's view point>002.60ft>Lat arm>-000.60ft>vert arm>001.47ft
Exit>Click on X upper right

To reduce the tire noise effect / squeal during Taxi and Xwind. Typical in acft 10deg with rudder pedals. Can be reduced further if needed.
Landing Gear>Gear Loc>n-w steering slow and fast>25.0 and 10.0...

Increase the friction to reduce the drift in Xwind and increase T.O. distance.
Landing Gear>Gear Data>Landing Gear friction coefficient>rolling co friction>0.200
Exit>Click on X upper right

To minimize the abrupt pitch up due to flaps being extended.
Control Geometry>Controls>flap extend and retract time>06.0 and 04.0
Exit>Click on X upper right

To reduce the time it takes for trim action on Pitch.
Control Geometry>Trim&Speed>Trim Deflections for aeroplanes>elevator trim full deflection time>12.0 sec.

Adjust for tendency to fly Right in straight and level flight. Tested in No wind, at 2710 RPM, 131.5kts, Standard day 1000ft. MSL, and better T.O. behavior.
Control Geometry>Trim&Speed> Trim Deflections for aeroplanes >aileron trim tab adjust 0.005 and >rudder trim tab adjust 0.000.

Nose wheel deflection time to minimize the tire noise effect / squeal during Taxi and Xwind.
Control Geometry>Trim&Speed>nosewheel steering full deflection time>1.2 sec.
Exit>Click on X upper right

File>Save
File>Quit

Null zone workaround.

Calibrate the Joystick and rudder pedal with larger Null zone by moving the controls when asked to keep it centered. This takes some trial and errors to get it right and you will end up with a Large Null zone message that you can ignore.

Fixing the scratches and smudges on the windows / glass.

I used the DX1bmp Bitmap monitor program and left the Alpha channel alone, and PhotoShop as editor. For the .png files after you modify and send the norm.bmp back to Dx1bmp you should save it as .tga, and after that you can use the PhotoShop or other editors to convert it back to .png.

File Location: X: ....\X-Plane 11\Aircraft\Laminar Research\Cessna 172SP
Files involved: "Cessna_172SP_G1000_prop_disc_2.png", I used dark Gray color to fill in the White and Red outer circles to eliminate the nasty red circles from the prop. I left the Alpha untouched.

File Location: X: ....\X-Plane 11\Aircraft\Laminar Research\Cessna 172SP\objects\instruments\garmin1000
"G1000_screens.dds" I filled in with Black multiple time to get all the smudges off, and left Alpha alone.

File Location: X: ....\X-Plane 11\Aircraft\Laminar Research\Cessna 172SP\objects
"glass_inn.dds" and "glass_out.dds" were a mess and can take a while to fix, but it's worth fixing for better view of the scenery and for your own sanity. The scenery looked like you see it through a dirty glass. The tint and scratches make the scenery / forward view look worse and seeing the scratches is not anything like in the real acft, that you normally see. I just filled in the Alpha and the norm / background, with Black. It takes a while to remove that trash.


Scenery modifications to give you good day VFR reference view points / ground references, Photoscenery using Ortho4XP, and better terrain recognition of hills, valleys, mountains.... using HD mesh, available at many sites for download. You may also want MisterX_Library and OpenSceneryX.