An enthusiast site about what changes, and what it costs
Carzone Specials covers what a tuning house actually alters on a car and what each alteration takes from somewhere else in it.
The underside is where the certification questions actually live. Most owners never see it.
The interesting firms in this subject are the ones with type approval behind them. Alpina in Buchloe, Brabus in Bottrop and Ruf in Pfaffenhausen have all held vehicle approval in their own right, which puts them in a legal category an aftermarket fitter does not occupy. AC Schnitzer in Aachen, Abt Sportsline in Kempten, Techart in Leonberg and Hartge in Beckingen work at component level. Nismo and TRD are the motorsport arms of Nissan and Toyota, so the approval question never arises for them at all. The guides name these firms factually and do not rank them.
How the site is organised
Four sections, unequal on purpose. A plate is the difference covers approval and liability. Most of the money goes on the outside is the largest, because that is where the budgets go. What each change takes from somewhere else deals with induction, suspension and brakes. Why the factory did not is the shortest and, arguably, the point of the rest.
On figures
Power, torque and time figures appear here only where a named manufacturer or a named publication produced them, with the method. Most of what these guides describe is qualitative because the honest version of it is qualitative: a wider wheel takes something from the ride, and the size of that something depends on the car.