Summary: The sound the Driver makes is like your hitting your golf ball with a tank!
The price has dropped quite a bit since it was introduced in 2008,I believe, so if you can find one in a golf store or online - give it a try.
I chose one with the stiff flex , The regular flex has too much play in it.
Golf Driver Reviews of the Callaway Hyper X Driver
18 December 2008
Summary: The Hyper X is Callaway's upgrade to the Big Bertha 460 but still carries on the tradition of forgiving stroke play. Callaway says the Hyper X has the largest hitting area of any titanium driver they have ever made, which creates higher ball speed across the face.
Conclusion: Callaway Hyper X Driver : Callaway Golf engineers set out looking for breakthrough ball speed enhancements that would set a new standard in a crowded all-titanium driver market. The innovative Hyper X Driver provides a new benchmark in performance with the introduction of Hyperbolic Face Technology,...
Conclusion: This driver took almost eight years to perfect but the engineers but no waste of time here since the engineers have come up with a club face that is more efficient resulting to greater distance. It has a 460cc head shape so expect a higher center of gravity
Callaway Hyper X - Why the Callaway Hyper X Driver Won My Heart…
14 May 2008
Conclusion: Yes, the Hyper X won my heart. All science aside, it makes me more comfortable teeing off than ever. I’m not a big hitter and I don’t necessarily generate a lot of clubhead speed, but this driver made be feel like I was one of the guys. Very fun indeed!