Does anybody know if the OEM manifolds from later years F2, F3, F4 would fit an F1 motor? Reason being is because the F1 header is a 4-1 design. The later model headers from other bikes were 4-2-1 designs.Ifany of these later headers were interchangable with the F1 motor, could it be possible to increase power by going from a 4-1 to a 4-2-1? Looking at pictures on eBay, it almost looks like the only thing that would be changed is the angle in which the muffler slips on?