I had Friends that owned Mach 1's with 351w and 351c engines all of them where stock or near stock and 4V engines . The 351w's where not very fast . Know the 351c 4V Mach 1's Raged . You hear how the 4V Cleveland heads with them Big Ports killed the Low end Power ? You would never now it watching them cars run . Even that 1972 Mustang 351 HO was and still is a Bad Boy right out the Box .