If you decide to use a big-bore carb, you will have to replace the restricted manifold with an unrestricted one. Otherwise the large carb will be useless since its venturi size is actually reduced to the diameter of the restricted manifold. Our manifolds will fit any Dell'orto carb up to 21 mm. The derestricted manifold gives better acceleration and better top speed. Compatible with: - Aprilia: Area 51_S, Rally 50 AC_S, Rally 50 LC_S, Scarabeo 50 Min.AC_S, Sonic 50 AC_S, Sonic 50 LC_S, SR 50 Min.LC_S - Beta: Ark 50 AC_S, Ark 50 LC_S - Malaguti: Centro 50 AC_S, F10_S, F12 AC_S, F12 LC_S, F15 Firefox_S - Mbk: Mach G 50 AC_S, Mach G 50 LC_S, Nitro 50_S