That is very useful information. It is funny you mentioned that too. Yesterday I went out to work on my cars and I was looking at the stinger on my adam drake pipe and it was really small. I took a drill bit to it and started drilling it out 2 drill bit sizes bigger. I think it is still too small so I will go look at what the sirio pipe stinger is because i know it is much bigger and probably around 7.0mm. With my adam drake pipe, I may drill it out to 60% of the header ID which will probably eliminate the stinger all together but I will just weld one back on so it can perform the way I want it to. Or I will try out the sirio pipe, see how the works then modify the adam drake to the same performance. Thanks for the info and I will let you know about the sirio BB pipe ID.