I have been building clubs since 2004 and until recently, I really did not know the answer to this question.  According to research and an Ai Search, this is what I discovered:

To achieve a noticeable "trampoline effect" on your driver head, you generally need a swing speed of around 105 mph or higher; this is because most standard drivers are designed to maximize their spring effect within that speed range, allowing for greater ball velocity and distance.

If you have a lower swing speed (like most of us) you can gain yards by going with an oversized head which stretches the volume up to 515cc to gain more trampoline effect as the face may be thinner.  Or, Krank Golf, with their genius engineered Formula Fire drivers offer three different face thickness to match the players swing speed. Pro for drives over 260 yards (LPGA Legal), X High Core for drives 200-260 yards, and XX Super High Core for drives 200 yards or less. 

Keep in mind that LPGA limits the driver head volume to 460cc, plus a tolerance of 10cc, so drivers in the "Illegal Equipment" section on my site, or some Krank drivers are not going to be legal for official an some non-official tournaments.  But, if you are just looking to gain some distance, why not?!