Aftermarket exhaust parts and the engine. However, the pipes do "ring" with the exhaust pulses and increase underhood noise. Headers can be ceramic coated to reduce the heat radiated in the engine compartment, and to increase the temperature of the pipes which increases the velocity of the exhaust gases. Terminology: Catalytic converters are necessary to reduce emissions but create back pressure due to the exhaust gases being forced through a catalyst, and therefore decrease high-end engine power. Many modern catalytic converters only produce 1-3 psi of back pressure, though this restriction worsens further with use. Hi-flow catalytic converters can replace the standard units
Alternatives to car use (petroleum-powered) car and contribute to transport sustainability. They also provide other significant benefits such as reduced traffic-related injuries and fatalities, reduced space requirements, both for parking and driving, reduced resource usage and pollution related to both production and driving, increased social inclusion, increased economic and social equity, and more livable streets and cities. Some alternative modes of transportation, especially cycling, also provide regular, low-impact exercise, tailored to the needs of human bodies. Public transport is also linked to increased exercise, because they are combined in a multi-modal transport chain that includes walking or cycling. According to the MIT Future Car