Advice, Kill the female.

^ length of vagina does change via height, fun facts

did you not even see my post, choco xD?

He did, he just didn't care to respond. All you really need is around three inches to really hit the most sensitive spot (G-spot), although some G-spots can be a little deeper or a little closer to the vaginal entroitus. Of course, some women get a big reaction from G-spot stimulation and some don't. Results may vary. I'm not to sure about height corellation and depth of the vagina, but I've only been with two women counting my wife and they really seem/ed about the same, except for G-spot distance from the entroitus. I like these kind of studies, I can volunteer to find out (With my wife's permission, of course), for science. ;)