I ran mine with 1 shim 112 mains and a 2" hole drilled in the lid, snorkle removed. If you are too lean the bike will surge at highway speed, too rich and it will just be down a little on power. After you run it in a while, check your spark plugs for color. They should be a chocolate brown- white is lean and black is rich. I would not cut the springs with an airbox. It will hurt your throttle response, which is the main performance reason to keep your airbox over the pods IMO.