Go with the Freak for sure I put it on mine and fit almost perfect. The 160s are too big. I run straight pipes and the Freak with no AI and I was rich with 160s and I'm at just under 2,000' elevation at most and do most of my riding at 1500' to 1800'. Mileage is a tough question since so much depends on how you ride and how hard the engine is working. If you are running hard you will use more than if you are just putting around with the same carb. set up.At my altitude and set up 155 mains is about perfect and I have 48 pilots I might drop those down a size not sure yet.

I learned all I need to know about life by killing smart people and eating their brains.
Eat right ,Exercise ,Stay fit, Die Anyway!