• 
  Xceldyne Technologies
  http://www.xceldyne.com
  Camshaft belt drives and valvetrain components
• 
  XRP
  http://www.xrp.com
  Performance hose and fittings
• 
  XS Power Battery
  http://www.4xspower.com
  Racing batteries and chargers
• 
  Xtreme Racing Products
  http://www.safetyfirstusainc.com/Xtreme_…
  Data acquisition tachometers