[doughboy]

I found 90 is the max i felt safe at.

We've got a top of the range, super aero, award winning Kamei Corvara duo lift box and its plenty rigid, but the nose of it (which you can see out of the top of your windscreen) gets buffeted by the wind and starts bobbing up and down above 80 or so, and it bobs more and more the faster you go, it might stop above a certain speed though, just not tried it yet.....

We don't have any music on (missus doesn't like it) so although there's no whistle, there is an audible 'roar' to the windnoise of the box, its really loud with a window open, but windows closed (or music on) its not a problem.

You can feel the extra drag when you come off the gas at about 90 the car slows down so much quicker than normal it feels like you're going up hill.