I talked to a performance motorcycle workshop, and they told me that a new exhaust (probably Staintune), and a performance airfilter (K&N, plus some work to the carby, such as re-jetting, and some dyno-tuning, should increase the the power to about 30 kilowatts, compared to the stock 23. He said it would cost around $1,000 Aussie to do this. I figure it´s probably cheaper and less of a head-ache to trade-up to a bigger bike.