Apico CRF450 04-16 CRF450X 04-18 Performance + Clutch Kit Excluding Springs . Apico Performance+ clutch kits offer the complete solution as with our Factory Racing kits, with the added benefit of having aramid fibre papers on the friction plates. This enables them to work at higher temperatures and makes them more durable than standard giving an overall better performance. These products are specifically developed for motocross and enduro bikes.