Has anyone ever did this? I currently have my manifolds off , and was debating whether or not to take it in to a local machine shop if theres performance to be gained from doing it myself. Just from glance, I noticed theres a decently big lip right in the inside where it connects to the downtubes...can I remove this? Basically my question is, can I do this bymyself or is better left to professionals? I do have a dremel to so it just got me thinking. And if I can do it myself, what areas are to work on? Obviously I cannot reach way down inside. Thanks.