the wheels will help a lot more then the exhaust. Has to do with the science of less mass rotating. The bike is going to feel lighter completely. On the other hand, it may feel a little to floaty at high speeds.
I don't think having the rear raised will look funny at all. Everyone that does it states that the bike dives into the corners much better then it did. You are only raising it an inch. I would do the exhaust as well, but I don't think this is going to give you much in the handling department if you ask me, but it will lighten the bike a bit.
I wouldn't go replacing the swing arm if I were you. If you may find yourself ruining a perfectly good Busa. I think you can get what you are looking for out of the these other methods successfully. If you raise the back at a cost $40 and that doesn't do what you want, then start thinking of trying some of these other things. I really think you will be amazed with the difference in raising the rear though... my 2 cents.
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