Yes the engine has a roots blower/carbs.The casting is rough around the valves and will improve a bunch in the low/mid range cleaning the chamber up and throat.The test bore size will help/hurt flow also so maybe it was done with a larger bore tube.The engine is a 446 3.75 stroke,9.4cr with the heads haveing a choke of 3.14sq.in. with 6800 rpm,.630/112lsa cam so I am sure my port air speed will be fine.