If we rate them by "Bang for the Buck" then first are the Magnum and MDS, followed by Saito and YS.

Then after a long gap we find the OS engines. Until they go back to a chromed cylinder liner I will not recommend them. And they need to cut the %$$# out of their prices - too many other engines with similar performance, true ABC construction, and prices 1/2 to 2/3ds as high.

My rating is based purely on power per dollar. That's what makes the 2s engines beat the 4s engines.

Bill.