I have the Ultra Zone, Python, and Rattler which are all drilled pretty similar. In my experiences, the Ultra Zone has more backend movement than the Python. And, the Rattler is more angular when it reaches the dry boards. If you are looking for something close to the Ultra Zone, then I would go with the Python because of the stronger core than the Rattler. Both are really good bowling balls for the money. I would put a little stronger drilling in the Python from your Ultra Zone because of the symetrical core vs. the Asymetrical core. Another ball that might be as strong as the Ultra Zone would be a Wild Ride if you can still find one because of the Asymetrical core.
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Brunswick user and supporter.