I have an ESP Viper hardtail with the Sentient and Pegasus pickups that I bought for drop tunings. The strings are 10's but dropping to C gets them too flubby for me. Are you using 12's on yours for drop C? I think I need to swap.
BayouTexan i use 10’s on my Drop C guitar but you should experiment with string gauges if you aren’t happy. Be careful though, the higher you go the harder it is to bend the string to the right pitch