All new cylinder head stage 2 cam valve's spring's & intake,  Stage 2 plus porting will flow over 20% more air than stock and will be smoother acceleration, Valve seat's have been individually lapped to each valve to ensure fit, All part's are manufactured in Taiwan not China (Not Niche) This kit will work best with high compression or big bore piston,  Will fit all year's of 400EX & Sport Trax 400X,  New quality and performance at a low cost,