The more weight you shed the better...
i think this is key. all i've taken off so far is the front fairings and stock headlight bracket (replaced w/ a yamaha fz16 headlight for a naked look).
the difference is noticeable; it definitely had a positive effect on the power profile and how the bike leans/turns.
i'm really looking forward to taking the stock exhaust off... should be an even more significant loss of weight.