Tuning Kit (pre 4.9.0) (Asphalt 8)

The Tuning Kit is a performance-enhancing booster introduced in Asphalt 8: Airborne. 
== Usage ==
The Tuning Kit is a special booster that enhances the performance of all playable vehicles by up to a maximum of 30% (27.5% when maxed out) in every upgrade category (Acceleration, Top Speed, Handling, and Nitro) for a limited period of 15 minutes.
The Tuning Kit can be activated using a boosts menu that appears before every race. It appears alongside the Double Credits Booster, Nitro Starter and Extra Tank.
The Tuning Kit can be obtained by purchasing it for anywhere between to , depending on the player's progress.
The Tuning Kit can also be obtained for free from various sources, including Time-Limited Events, Daily Bonuses, Daily Advertisements, Mastery, Collections, and Multiplayer League. If obtained in this way, the Tuning Kit's usual green purchase button is replaced by a white button displaying the number of free Tuning Kits available. The Tuning Kit can also be obtained by "Tuning Kit-only" daily advertisements (you get 5), with the advertisement button appearing next to the Tuning Kit in the boosts menu. These types of free Tuning Kits don't have a timer; instead, they are "one use only" but they also do not "decay".
If the Tuning Kit boost is activated, a boost icon will appear in the main menu along with a timer indicating how long the boost will last. A timer will also appear on the Boosts-screen indicating the remaining time of the activated boost.
== Mechanics ==
==== Performance Boost Calculations for Cars (excluding Bikes and Formula One Cars) ====
With the car at stock (no upgrades), the Tuning Kit works by boosting the car's MAX statistics each by one level. A car with "0000 0000" as its tuning will be boosted to the equivalent of "1111 0000" temporarily.
When the car is upgraded to MAX + PRO, the Tuning Kit works differently. Instead of increasing each MAX statistic to the equivalent of the next level, the Tuning Kit increases each MAX statistic to an imaginary "6th MAX level".
Because of the way that the Tuning Kit bonus works from MAX levels 0 to 4, the Tuning Kit bonus' boost amount is directly influenced by the gap between the stock and MAX ranks of the car. Logically, a larger gap in the MAX ranks means that the Tuning Kit will imitate that large MAX rank gap, giving a larger Tuning Kit boost. The level 4 MAX Tuning Kit size boosts the car's performance to level 5 MAX, so the Tuning Kit boost at a tuning of 4444 0000 is the equivalent of 5555 0000. Compared to the difference between the stock and level 5 MAX levels, the Tuning Kit bonus at 4444 0000 is the equivalent of exactly 30% of the boost gained from those MAX upgrades.
At MAX + PRO, the Tuning Kit is still influenced by the difference from stock to MAX. However, the imaginary value which is created is always less than the value gained at 4444 0000. The imaginary value is usually the equivalent of 27.5% of the difference from stock to MAX. This means that the Tuning Kit bonus at 5555 0000 is the equivalent of the Tuning Kit bonus at 4444 0000 multiplied by 11/12 (91.67%).
==== Other Useful Information ====
It should be noted that cars with lower starting ranks usually only have larger Tuning Kit bonuses for the raw top speed statistic. The acceleration, handling and nitro statistics usually remain constant across all cars.
A good example of this is seen when the Volkswagen Beetle Turbo (D1230) and Renault CLIO R.S. 200 EDC (D1202) are compared. Although the handling statistics are different (they should be disregarded for this example) the Beetle and the CLIO share the same nitro statistic and acceleration statistic. Despite the fact that the Beetle has a much lower starting rank than the CLIO, which allows it to be Multiplayer tuned, the Beetle's nitro statistic does not start at a lower level, nor does it end at a higher level. Even the Tuning Kit bonus remains constant. The same is seen with the acceleration statistic. The only difference which the Tuning Kit creates is a 6.2 mph (10.0 km/h) increase in the raw top speed and the total top speed (the Beetle is faster than the CLIO).
With a highly nitro-based car like the Renault Trezor, Renault DeZir, or Porsche 959, the situation is the same. Despite nitro seeming like the dominant statistic, the real situation is that the raw top speed has been reduced, allowing the nitro to essentially replace raw top speed when upgraded. The nitro statistic still remains constant across cars with the same-sized nitro.
Another important thing to note is that PRO upgrades don't increase the Tuning Kit bonus. Therefore, it's usually better to upgrade MAX levels first (the forced coefficient can make Pro Kits the more efficient upgrade-type, however). It should also be noted that Upgrade Rank Percentages play a very large role in Multiplayer tuning cars, so that is why most cars are best tuned towards either raw top speed or nitro, but not both.
Another point is that the nitro statistic can greatly influence the performance of a car and the size of its Tuning Kit. For example, the Porsche 911 GT3 RS has a fairly large Tuning Kit size, yet it doesn't receive a speed boost as large as the Lamborghini Asterion or Lamborghini Aventador LP 700-4. The reason for this is that its nitro is large and its raw top speed is low. The nitro increases the displayed Tuning Kit size (the number), but the Tuning Kit bonus isn't actually supposed to be that large. This also means that, in Class B, the Shelby Cobra 427 technically has a larger Tuning Kit bonus than the Honda Integra Type-R, despite it appearing smaller.
The last point is that cars in Class D have greatly increased speeds if they have large nitro statistics, while cars in other classes have slightly reduced speeds if they have large nitro statistics. For Class D cars, the speed can be increased by over 10 mph (16 km/h) if the car has an unusually large nitro, as seen with the Ford F-150, Renault DeZir, and Porsche 959. For the other classes, the speed can be reduced generally by up to 5 mph (8 km/h), as seen with the ED Design Torq, Honda Integra Type-R, and many other cars. This is relevant because it can often seem that the Tuning Kit or Multiplayer tuning are the only things responsible for the increased speeds of the three Class D cars mentioned, when, in reality, it is largely due to their massive nitro statistics. Also, for nitro-based cars in higher Classes, this is relevant so that players are not fooled into believing that the cars are very good for Multiplayer just because they have large Tuning Kit bonuses.
== Records ==
* The Renault DeZir has the highest displayed Tuning Kit bonus at 128 points, beating the Ford F-150's 95 points, with only a 33 point difference between the two. All of the other cars receive a kit bonus smaller than these two (excluding the Audi R8 e-tron Special Edition, which equals the F-150, with 95 points).
* Highest Tuning Kit bonuses for each class:
** Renault DeZir (Class D): +128; Speed gained (MAX): 47.0 mph (75.7 km/h)
*** This is due to the tiny PRO rank increase of 109 (there are only 2 Pro Kit levels) and the car receiving 25.7 mph (41.4 km/h) worth of raw speed and 21.3 mph (34.3 km/h) worth of nitro speed.
** Range Rover Evoque Coupe HSE Dynamic (Class C): +84; Speed gained (MAX): 46.1 mph (74.3 km/h)
** Honda Integra Type-R (Class B): +77; Speed gained (MAX): 42.6 mph (68.6 km/h)
*** Note: As the Integra is a nitro-focused car, the Integra's tuning kit appears to be the highest in its class. Adhering to the tuning kit rule regarding the amount of speed gained from maxing out the car's top speed and nitro stats, the BMW M2 Special Edition and Mazda RX-8 Special Edition actually have the largest tuning kit bonus within Class B, at +75 points. 
** Audi R8 e-tron Special Edition (Class A): +95; Speed gained (MAX): 77.6 mph (125.0 km/h)
*** This is due to the low starting rank at 459.
** Aston Martin Vulcan (Class S): +62; Speed gained (MAX): 56.8 mph (91.4 km/h)
* Lowest Tuning Kit bonuses for each class:
** Suzuki GSX-R750 (Class D): +35; Speed gained (MAX): 14.2 mph (22.9 km/h)
** Vencer Sarthe (Class C): +20; Speed gained (MAX): 12.0 mph (19.3 km/h)
** BXR Bailey Blade GT1 (Class B): +20; Speed gained (MAX): 15.1 mph (24.3 km/h)
** RUF RT 12 S (Class A): +25; Speed gained (MAX): 19.5 mph (31.4 km/h)
*** For players that do not have the RT 12 after the Porsche Update, the Zenvo ST1 has the lowest tuning kit boost among all Class A vehicles in the garage, at +26 with a MAX speed gain of 20.4 mph (32.9 km/h).
** Arash AF10 (Class S): +18; Speed gained (MAX): 15.5 mph (25.0 km/h)
*** This is also the lowest of any vehicle in the game.
== Trivia ==
* As of the Dubai Update and Winter Update, the tuning kits have been changed significantly. For example, Tuning Kits applied on a maxed out McLaren P1™ (Rank 1611/1611) now award it with only 33 points, making it 1644, as opposed to the pre-Dubai Update's bonus of 50 points.
** Also, when maxed out, Tuning Kits only award +27.5% of each aspect to the car, as opposed to 35.0% before the Dubai update.
* Three boosters (Double Credits, Nitro Starter (simply called "Nitro" at that time), and Tuning Kit) were added in Update 1 in November 2013, when the game was made freemium and new cars were added along with Time-Limited Events and customizable controls. (source 1, source 2)
* In earlier stages of the game (around February 2014), the Tuning Kit powerups received as trophies in the Time-Limited Events lasted for 8 hours. At that time the Nitro Starter would last for 2 hours and Extra Tank for 4 hours. So, Tuning Kit powerups' duration has been reduced to 1/32 of the original values (a ~96.9 % reduction in duration), and Nitro Starter powerups' duration has been reduced to 1/12 of the original values (a ~91.7 % reduction in duration).
* The cost of one booster minute before and after the latest booster update:
*: Old Nitro Starter: 15,000 credits / 120 min = 125 credits/minuteNew Nitro Starter: 7,500 credits / 10 min = 750 credits/minuteOld Tuning Kit: 40,000 credits / 480 min = 83.33 credits/minuteNew Tuning Kit: 10,000 credits / 15 min = 666.67 credits/minute
*:: The cost of one Nitro Starter booster minute has increased by 600 % and the price of one Tuning Kit minute has increased by ~800 %.Source: Touch Arcade: Universal Asphalt 8: Airborne - (by Gameloft), page 1317 (the duration of the Nitro Starter in the calculations on that page is (erroneously) stated as 15 min).
* After The Great Wall Update was released in March 2014, the 2 hour Nitro Starter cost 9,000 Credits and the 8 hour Tuning Kit cost 24,000 Credits (source: YouTube (rrvirus): Asphalt 8: Airborne v1.3.0 (The Great Wall Update) [@ 1:09]). Compared to the price level roughly a year later, the annual average inflation rate for Nitro Starter is 900 % and the annual average inflation rate for Tuning Kit is ~1233 %.
** Nitro Starter: 75 credits / minute → 750 credits / minute = 900 % annual average inflation rate = the prices are doubled every 3⅔ months.
** Tuning Kit: 50 credits / minute → 666.67 credits / minute = ~1233 % annual average inflation rate = the prices are doubled every 3.26 months.
*** This rate is well above the limits of hyperinflation, and in real life numbers like these would cause major difficulties in the economies in question.
* A car that has been upgraded to Level 4 on all aspects and has a Tuning Kit on will behave exactly the same as a car with maxed out stats and no Tuning Kit.
** This is assuming that Pro Kits aren't applied.
* In Infected mode, Tuning Kits increase the car's top speed when infected, but the infected speed bonus is always a fixed 22.2 mph (35.7 km/h).