I have used a supertigre carb, an OS7L and OS7D carb on my OS160. All the carbs with spraybars pulled fuel better than the 91-160FX carb. My testing method was quick and dirty, I simply raised and lowered the tank and measured the distance I got between too rich and too lean. The 7L was the best followed closely by the 7D, the Supertigre carb was good but restricted the engine by 200 rpm. I made the mounting universal by tapping the existing holes 10-32 and using set screws.