how much more do t top cars flex than hardtop cars, is it noticeable like with convertibles or is it nothing really to worry about (in a high horsepower car)

Unfortunately all of our cars flex, it's their give nature since they are a uni-body. I have no idea how much convertibles flex, but I'd imagine just as much as a t-top would. Of course the hard top does the least amount of flexing because of the extra surface area/support. Don't get me wrong though, they all flex, all definately need Subframe connectors welded in to help this problem

I'd say the T-top is much more like the hardtop than the vert. Verts flex like crazy. But, like Legal Disaster said, they all have some flex and they all would benefit from SFC's.