Aftermarket parts meet two distinct needs: replacing worn components or upgrading capability. A performance exhaust affect power delivery as well as headline figures. Suspension typically returns the biggest gain for the average rider. Choose parts according to actual use and not maximum spec.
Engine rebuilds form part of ownership rather than a failure. Two-strokes require more frequent rebuilds than four-stroke units. A full rebuild kit includes everything needed for the job. Checking bore condition before ordering decides if boring is needed.
Choosing the right tire changes handling far read more on dirt bike upgrades than almost any other component. Soft compound patterns use tall widely spaced knobs which clear mud. Hard pack tires run tighter tread spacing for a larger contact area. Running the wrong compound sacrifices performance and longevity.