To cram more mixture into the cylinder a turbocharger or supercharger is used to increase the intake air pressure.
A supercharger is belt driven from the crankshaft thus using engine power. The advantage is a relatively easy installation.
The turbocharger uses the "free" power of the exhaust flow to turn the turbine that spins the impeller to provide the boost. A turbo charger is more efficient from the standpoint of using exhaust gas for motive power, but the down side is the complicated exhaust piping that must accomodate it. Also a turbo needs oil pressure to lubricate and cool its bearings.