There all fairly strong. I have the LevRG and it is one of the strongest overall reactions I've ever seen. The Nsane is supposed to be stronger in the back. The Ntense should be stronger up front than either the LevRG or Nsane. Not sure about the Response...
Another thing to note: I've noticed more people have success when drilling the LevRG line fairly weak. The core is so strong that stronger drillings render the ball a turd, or so I've heard.
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Penn State Mens Bowling Team