Hi Olli;
There's tons of info (including pictures) on the Performance Pack over here;
http://www.cbr125world.com/store/produc ... ucts_id/31There's also a bunch of reviews in addition to the stuff scattered about this forum
The Performance Pack comes with revised ignition which increases the acceleration rate, true heavy-duty clutch springs which eliminate clutch slip (a real problem on these bikes) and revised gearing to increase the acceleration rate further. During development of the 'Pack I ended up cleaning the clock off my buddy's 200. He could not keep up with the 125 at that point - despite his 75cc advantage.
Most folks that have had Ninja 250's and the CBR 250 (not the RR) find that it brings the bike more into line with those models. It's the least expensive and most comprehensive modifications that can be done to the bike that have the highest rate of return as they address all the weak links in the original design.
The Carbon Fiber clutch kit is really durable. It's still pretty easy to kill off the OE clutch even with the HD springs under severe beatings especially in hot climates like AUS. If you elect to go with both be sure to buy the Carbon Fiber clutch Kit and the
Performance Pack less springs as this will save you money.