A modified car,bike consist of any of the components associated with car,bike tuning , however common upgrades include replacing the standard factory issue wheels with aftermarket alloy wheels, usually of a larger diameter to improve the aesthetics ; lowering the suspension of the car,bike to give it a more aerodynamic, stable look by replacing the springs (often in conjunction with shock absorb
ers) or torsion bars ; replacing the existing exhaust system with one with less gas-flow restriction, louder and deeper sound and often small improvements in performance (due to exhaust gas-flow rate). Other common upgrades include the installation of a short shifter as well as an aftermarket shift knob , or a performance oriented Weighted Gear Knob . Common non-mechanical upgrades include a cars audio system; though not performance oriented, are nevertheless a very common-place modification. This includes upgrading the head unit itself, and upgrading and/or installing additional speakers. Significant modification to a car,bike could involve adding a fiberglass body kit to improve the aesthetics, a complete respray to a more unusual, distinctive and noticeable colour and finish, increasing the engine performance with ugraded components such as a high-flow air filter , additional components such as turbocharger kit , as well as more permanent modifications like port and polish . Traditional customizing methods, more common when modifying classic cars,bike to create cars such as Hot rods , include roof chops , two door stretches, suicide doors , channeling and lights, trim and sheet metal from another car,bike.
