Love 'em, used them for 2-3 years in about 8 balls, had one weird one that goes in both ways, but that was the installers fault. I'm a definite fan of the concept and think Turbos are the besto of the crop (so far)...
However, I just ordered the Grip Loc system to switch over to give them a try.
Cons:
Pro shop knowledge, and therefore availability to have them done and/or changes made, is weak at best, and totally dependent upon your area. (possibly same problem for Grip Loc)..
Turbos use 1-1/2 inch drill bits, which 3 drillers have already said they can't use in their jigs (reason unknown).
I've only had one year at Nationals where I could buy a ball and find anyone on premise who could do Turbos...
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Signature? I don't need no stinking signature...