I vote for air box removal. Either get a kit like the Freak of Tom's battery relocation kit. I used the space for other stuff plus feel the engine breathes much better. You can gut the stock exhaust for free and I like that better than the after market pipes plus you save the money. Even if I had the money for after market exhaust I would still want my gutted stock pipes. Definately re-jet the carbs. You can blueprint the engine if you have the mechanical ability giving a good HP gain.

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