I went with the 118 per instructions but plan on giving the 120 a try. Plug looks like it could take a little more fuel. I also made the airbox mods suggested above, however I only removed the screen from the baffle so I wouldn't have to worry about cleaning it. Still want the exhaust reasonably quiet as I use my Eiger primarily for deer hunting.

 

I have a vinson and I took the snorkel of the airbox, and it just made the bike a bit sluggish. For me it it did not good.

 

did the 118 jet and k&n air filter make a noticeable difference or is like a placebo--you just think it is quicker because it should be.