This movie was celebrated first in the great book Bad Movies We Love.
We do love karate chopping drag queens (particularly those who can carry a tune SINCE SO MANY CAN NOT). hehehe... HooRAY!
I saw this movie on TV in the mid-70s... and later I found a 1965 Reader's Digest with an article which included "Sylvia" among the current crop of disturbing, smutty movies.