Well I have some experience with a few of these techniques.... The pipe cutter method does definitely work...as it widens up the oil grooves and pushes the material outwards, which increases the diameter of the piston at the area of the oil grooves...This definitely does work, but doesn't seem to last overly long before it wears down.... The ball bearing trick doesn't seem to work well on the higher end engines, the aluminum is far too hard and brittle, it would crank before it would stretch....Very similar material to Hypereutectic pistons...Hard with great wear properties, but quite brittle....... 100% the piston is the part that wears out, it is much softer material then the chrome lined sleeve...The sleeve goes thru very little wear from to the piston, and usually any wear is caused from foreign material going thru the engine........The piston just isn't hard enough to make any significant wear into the sleeve....... I have my best results pinching the sleeve, but I use equipment that would be too costly for the average hobbiest....And even with the proper equipment there is a substantial learning curve to perfect the technique... I now have about 100 repinched engines in circulation now with nothing but excellent results, most times the lifespan of the repinch lasts longer then the original ......The amount of pressure and accuracy needed to properly crimp the sleeve is beyond anything you could do with a hose clamp/screw clamp........I have dyno tested the repinched engines many times over and they perform as strong or stronger then the original factory fitment.... Repinching the sleeve works awesome, but it is a little bit of a black art to perfect