Here is a list of the things that could be done to improve SYNCHRO...

Right-in/right-out junctions need to be coded as a new special junction type. Right now, SYNCHRO models it as a gap in the median (which is wrong), and causes problems with vehicles trying to change lane on the other side of the carriageway, with traffic getting stuck as a result.

Traffic flows could be broken down into different kinds of vehicles. For example, it would be nice to be able to model buses separately from cars. It would also be nice to have separate traffic flows for existing and development traffic. It would be nice if the development traffic could be dynamically assigned.

It would be good to have LOS values for non-signalised intersections, including roundabouts. Since SYNCHRO is based on HCM 2000, and HCM 2000 contains the calculations for these junction types.

Finally, there are major improvements that could be made to the 3D Viewer. The cars should follow a smoother path around the corners, and the pedestrians and foliage need to be adapted for use in the Middle East.

i second the 1st one. I think i suggested the 1st one before.
2nd part is good also, but could be difficult to implement.
I think HCM 2000 does not provide overall intersection LOS for 2 way stops.
I could not understand the 4th point, Why just for Middle east it needs a modification?