Well, as per the suggestions of some on this chain, I have reduced the height of the windscreen I made to be the same as Mopar and etched versions.
There was a slight improvement.

The following are my opinions:
1. Without the side windows up, the windscreen is of little value, in reducing air current.
2. I prefer the looks of any convertible without a windscreen at all. I even feel like I'm cheating the car if I put the side windows up.
3. Any windscreen therefore, must be easy on, easy off. I have accomplished that.
4. If I had to do it over again, I would build mine thicker, like 8mm.