Spend a few bucks on a lesson. Have that instructor find what is off in your driver swing. It's really worth the $40-$50.
Get a shorter driver shaft. Once I started using a 44"- 43.5" shaft I was hitting the sweet spot much more often.
I recently inherited a Cobra Amp Cell driver from my father. The standard shaft length is a whopping 45.75"
I have been playing my Razr Fit at 43.5 with no added swing weight and its doing great. I love the consistency with the...