I am sure not saying that. I have only done the 2bbl version. I like them because of the ablity to increase the size of the transfer ports. The results I have goten are very good. A good running, light, and powerful engine. I think either convert well. I would have to see some numbers on the 1bbl version to decide which is best. My conversions get 7800 to 8000 rpm on an APC 16x8 prop. They will pick up around 1000 rpm or more after break-in it complete. That will take 4-5 gallons of fuel on non synthetic oil. Synthetic is not good until break-in is complete.