It does sound to me like the later models must have tougher welds. I have done quite a few so far and have never had any problems breaking them loose.(air chisel)Only issue I ever had was I just barely caught the wire mesh on the first pipe I did. Not enough to cause a problem all I did was bend that 1 spot back. I know most I have done were 03 and 04 pipes. If I get any newer ones I'll let everyone know what my impressions are about the differences in the welds if any.

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