Save money with one set! Buy the open intake manifold with the appropriate membrane block and save money!
The larger intake cross section of the diaphragm block and intake manifold ensures better filling of the cylinder and therefore slightly better performance. Another advantage is the fiberglass membranes, which do not damage the engine in case of breakage, as can be the case with the original metal membrane plates. Best value for money. ! !
No joint.
Quick note: the manufacturer provides the membrane block with a small aluminium bar that can be inserted into the membrane to "separate" it (center bar). It is not necessary to install it, we found no difference with or without.