Jeff, I've read a few of your posts on here and I respect your efforts to help others, so this certainly isn't a criticism of you personally. But, I'm not a fan of the 4-mix machines. I bought an FS 90 a couple of years ago and almost immediately regretted it. Not only is it fairly expensive to purchase, but, for my purposes, it is heavy, cumbersome and overly complicated. The Husky 223L I replaced it with is far lighter, better balanced and easier to use and maintain. I guess my comment was intended to mean putting valves in a trimmer just makes them heavier, more complicated and more expensive to maintain. EPA or not, the competition is getting by without the valves. Again, I respect your opinion and helpful post, I'm just not much for the 4 mix machines.