[GM Muscle]

imagine a box.. going from each subframe mounting point up to each corner of the roof.. can you see that cube? now.. take out the four bottom legs and you should have some sort of car port lookin contraption in your mind.haha.. the fire wall will add on leg in the front so put that leg back.. this is basically what your frame setup looks like.. does this structure seem sound? add weight on the out side of the front and back of this box.. seems even scarier to me.. now think if you put two of the legs back on the sides (sub frame connectors) .. plus all the weight being distributed evenly along the floor pans.. it takes that raggedy box and makes a solid structure..i know im probably over dramatizing it but you had the right concept in your mind but you didnt take into acount that your roof is a very active part of your unibody. the whole car including the fenders, inner fenders and floor pans add structral integrity.. but sheet metal can only do so much so when you ask which direction of flex id say all cause it helps complete the structure..