When Porsche calls something an Aerokit, you know it will have noticeable aero-improving effects on the car it’s fitted to. In the case of the 911 Turbo and Turbo S, two of the fastest Porsches ever, it adds downforce and promises increased stability, especially at high speed.

The German automaker says the Aerokit makes the Turbo and Turbo S generate 26 kilos (661 lbs) of downforce at 300 km/h (186mph), which is 9 kilos (20 lbs) more than stock in its “Speed” setting. Switch to “Performance” and you get 18 more kils for a grand total of 150 kg (331 lbs) at the aforementioned speed.

The kit can be had both in body color or high-gloss black and it will set you back €5,355 if you order it on a new car, or €4,879 if you opt to have it retrofitted by Porsche Tequipment. Warranty is obviously not affected in either case.

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