time for a stupid question- conv. top and speed
 

This being my first convertible I have to ask: is the top rated to be in the up position for the top speed the car is capable of achieving ? I assume the answer is yes but as the speeds get up over 100 you can tell the rear glass window is vibrating. I know there is a fair amount of air displacement going on so it's no surprise the window is vibrating. Really just curious of the answer.
And as a follow up are the roll bar screens and the center plexiglass wind deflector capable of staying in place at high speed with the top down ? Mine seem quite flimsy .

I doubt it. Too much turbulence with the top down even with windows up.

The regular Boxsters, 986, 987 and 981, can all handle top speed with the top up. The 987 Spyder's roadster top had a lower top speed limit with its top up than with it down. The 981 Spyder doesn't have a lower top speed limit with the top up. I've got nothing to add on top down, other than to say make sure the plexiglass wind deflector and the roll bar screens are correctly snapped in place.

My own 2003 S has its original top. I am tall and when seated in the car my head is about 1 inch below the inside of the top. I can feel some buffeting in the top fabric at 80 mph occasionally.

The roll bar deflectors have been known to blow out at high speed. Discretely wire-tying them to the roll bar is a good idea. The plexi piece should be ok if the clips are in good condition.

I would remove all 3 of the wind deflecters for a top speed run, especially in your Box. You need to increase tire psi too, I would ask Jake about that.