I don't think anyone takes the speedo into consideration. I have tested 4 BA/SM's and the best was off by 10%. Two of them by 13 and 14%. Thats quite a bit in my opinion.
My SM is not stock but I do not have the exact specs on jets etc. I averaged 130 to reserve but since I took the belt off and went with the 16 tooth sprocket I average 145.
