1. Buell conversion (or any other FZ6-FZ6N conversion)
2. T-Rex frame sliders
I absolutely love the naked bike look, so I think that a conversion is the mod I would do if I could only do one.
The T-Rex sliders almost completely saved my bike when I lowsided last spring. I still have one small scratch on the left side rear fairing, but other than that, my bike is in near pristine condition. I totally recommend the sliders to anyone who has an FZ6, or anyone who has a bike that T-Rex makes sliders for. I have a friend who laid his bike over and had sliders on his bike. They completely saved his bike (a Honda 599), with the only damage being done to the slider itself. Definitely the best bang for your buck mod!</endorsement>