problems uploading photos last night...need a new cable...should have them in a few days.
Anyway, the photos posted by speeddesignz capture the concept. Although I notice in his photos there are no shims under the rear brace between the posts and under the front brace between the MSX carbon fiber.
They are important, because, without the shims, the braces do not sit square to the alum pieces. Resulting in a tweaked chassis.
Its hard to tell in the photo, perhaps its the angle of the photo, but is the center post being used bending the MSX up plate? Which tube did you use, that's not a bad idea.