The P90D retrofit costs the full $10,000, plus whatever taxes and labor costs are involved with its installation. The upgrade, as Electrek details it, replaces the standard fuse with an "advanced smart fuse" that monitors and manages current more precisely (to the millisecond). The main steel battery pack contactor gets replaced with the same Iconel superalloy that Elon Musk's other venture, SpaceX, uses for its SuperDraco rocket engine. Combined, the changes increase the maximum output from 1,300 to 1,500 amps, which translates to better performance from the car.
The result: the upgraded P90D sheds 10 percent of its 0-60 miles per hour time, dropping it down to 2.8 seconds. Tesla puts the updated quarter-mile time at 10.9 seconds, and says the time to 155 mph is "20 percent faster than a standard Model S Performance."
And, of course, Tesla doesn't leave out the all-important underline to the P90D badge. Somehow, it just wouldn't feel as fast without it.