Crossover pipe has to have a flex if its using a vband on both sides as this is what allows the pipe to slide in and be pulled tight. If it can't do this then your essentially torquing the manifolds off the head to close the gap. If you don't have a flex in the crossover, the design is flawed as you'd have to have the crossover pipe perfect and thats assuming the SSAC ARE AN EXACT COPY which we all know is not true.