I flow tested 3 Tecumseh air filters, 1 Wacker cover, 1 West Bend housing and an Azusa velocity stack last night. I ran the tests on the HL-173A carb that Wilma sent me since it is bone stock and is what most Rokon 820 engines have. I did not use an elbow. I am looking for an air filter system that is currently available that does not hurt horsepower too much. I will run more tests on larger carbs since I suspect some of the Kart guys might also be interested in this.