I have or have had OS, Saito and Magnum. They are all good, I really like the Magnum for the price and I have three. The 91 is about 1 oz more than a 61-75 2 stroke from my findings. I still think you would be advised to obtain a regulator. The 2 stroke was misarable and continually flooded, quit, etc. The 4 stroke was much better but not great....