At one point i felt the same way and the out going whole is a bit bigger i should have got a updated photo. Eather way as i mentioned in my first post Ive ran this without a cowelling on the plane with the same results. This is why Im thinking a 24X10 MSC is a tad to big for this engine. However I will make a serious atempt at enlarging the out going if you still feel its the issue but here is a 3 min old pic sorry to have ussed an older pic