H2O is my guess. I do not have a SD to compare it to, but the flare potential on both is 4" (although, so is the Tsunami). With the Cobalt having a 7" flare potential, I can see it being ALOT stronger than a SD. Of course, drilling will play a big factor in all of this. I have my H2O drilled 4x4 stacked, and it is a strong, but smooth reaction (when the lanes are right for it). My Cobalt (drilled 5x5) on the same conditions will outhook the H2O by a ton! I wish I had more of the older balls to compare. I really like toying with different covers and drill patterns.
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Jon (in Ohio)
CHROME WON'T GET YOU HOME!
F.O.S. Proud Saw user...see profile.