OK i have a vip 23ft . with a 460 and yes the king cobra drive... So i just had the drive rebuilt and went out with machanic to test. results 56mph with the viper 14.25 23 pitch. @5000 rpm (band 4400-4800) so i order a 14.5 25 lexor..... and now i get only 3400 rpm. something aint right...