How To Build Harley-Davidson Horsepower shows the Harley-Davidson enthusiast how to modify Evolution-engined Big Twin for more performance.200 photos and expert advice from Harley-Davidson wizard Tom Murphy explain the ins and outs of tuning the Harley Davidson motorcycle. Includes carburetor modifications and aftermarket replacements, exhausts, ignition, big-bore kits, turbocharging, and supercharging.