2006 was the first minor change in the GasGas clutch basket where some of the older aftermarket cutch plates don't fit very well.
Also be forewarned that stock GasGas clutch plates are 2.9-3mm thick where most aftermarket fiber clutch plates for GasGas are 2.8mm or less, sometime much less.
Barnett, and possibly some others, compensates for this by offering a thicker steel plate than the stock GasGas so that their complete clutch "stack height" has the same thickness as the stock GasGas, problem is you have to buy their whole kit to get the proper "stack height."
Off the top of my head GasGas metal plates are 1.5mm where Barnett has 1.55 and 1.6mm thicknesses available.
Also be warned that most aftermarket fiberclutch plates have a smaller contact fiber "block" that sometimes has as much as 15 to 20% less surface area or contact area.
The upside to this may be more effecient cooling but I'm not totatlly convinced of that the trade off would be worth it especially if you run the aftermarket metal plates which have more mass and thus would retian heat longer.
Moral of the story; aftermarket GasGas clutch plates usually aren't a deal even at half the price especially if you like to abuse your clutch.