Does size matter? Yes. Size(length) enables you to go further into the vagina. And because most of her 'pleasure' is when you are entering her vagina, the longer the better. Now, Size(Width) is another yes. The reason? Because it is causing more friction along the vaginal walls. Which yes, for most women, gives more pleasure.
Now keep in mind... 5 1/4 inches(length) is the average size of a penis.
8+ Inches CAN kill a woman. I am not joking. Usually, it doesn't but it can. With enough preasure on the back vaginal wall, it can puncture and cause internal bleeding. This obviously causing the woman to bleed to death. So bigger isn't always better.
Now a myth I've been hearing for the longest time and I think its the funniest shit to hit. Black men have a bigger penis. When non-erect? Yes. This is because black peoples penises are the same size erect as they are non-erect.
-Storm