Hobbsy, my imaginary choice has been stated several times. It is between high performance and reliability, pretending that the two conditions cannot exist in the same engine. You say to stay away from YS engines because they are problematic (your words). So if you had your choice between a .91YS engine and a .91OS Surpass II engine, which would you choose if that were to be the only engine you could ever use? This assumes that YS engines are problematic (your words) and OS engines are much less problematic (perceived as such by a lot of folks).