what is it in the d16a6 engine that puts the rev limit at 6500 rpm? is it the limit on connecting rod strength at that rpm or does it have to do with the begining of valve float? i am asking because my si seems to be still pulling hard at 6500 rpm and i hate to cut back to shift. i feel that it could go possibly another 1000 rpm with power before shifting but i dont want to hurt anything. just thinking.