After you've been building and modifying cars for a while there's some things that you become pretty particular about. It could be just how you like something to look or function, or just an extra step you take to save yourself headaches in the future. One of mine is an exhaust system that's leak-free and sounds good. I've had bad luck over the years of header unions leaking over time. It seems either they crack at the welds or they just fit poorly and leave much to be desired when fitting the rest of the exhaust.