That is an impossible question to answer. There is too much variability in cylinders and other parts with the rotax. Mt prevo responded good to the upgrade, others better or worse. I have seen evo’s that run about the same as mine and other much worse than min side by side. If you have a good engine with a legal lettered cylinder then I am confident it will still be a good engine. Copmparing that to a brand new engine is difficult as you will be getting ht eluck of the draw on the cylinder you get with the new engine. Over the next year everyone that spends a lot of time, money and effort on rotax will begin to identify the good from bad cylinders. I have not seen a brand new engine that ran on the same track on the same day that was measurably better to my upgraded engine.