Starting from Horizon 3, FH games have had mostly the same PI system: the lowest class has the biggest range - D100-E500 - and all others have a range of 100 PI points, C501-600, B601-700, A701-800, S1 801-900, S2 901-998. While there is not much inherently wrong with how this is set up, this system has kind of proven itself to be unbalanced and inconsistent. Many cars from the lower end of a class will require significant upgrades in order to be competitive in the top of its class, often even an engine swap because the stock one proved itself to not be viable, while in real life it’s a tuner’s dream.
There is a lot wrong with how the PI system itself is working, but I do not expect anything to be done with it in this millenium. What could be done even within Horizon 5 is adding a few intermediate classes to more accurately represent performance of many cars when upgraded.
F100-F250 - for the slowest of the slowest, so that they can have their own ground to compete
E251-E400 - for the not-so-slow cars that wouldn’t really need to be upgraded to top of D class
D401-D500 - now without incredibly slow, borderline unusable cars
Classes C and B can remain unchanged, as they’re probably the most consistent classes in the game
A701-A775 - lowering the roof for A class would allow many lower class cars to perform well in what’s now the top of this class
S1 776-850 - lowering the roof for S1 class would significantly improve the competition of cars within this class, as currently it has perhaps the widest range of performance out of all classes
S2 851-900 - significantly lowering the roof for S2 class would create a much more balanced paying field within
R1 901-950 - a new race class that would allow super and hyper cars from PI below 900 to compete without the need for conversions
R2 951-998 - a new race class that would allow cars that don’t yet reach X class to compete against each other, while the lower PI cars stay in their competitive range
Applying these changes would only affects UGC and Rivals times in a cosmetic way. Files can be modified and reshared, and times can be improved with appropriate cars.
For future Forza titles, I suggest this PI class layout:
F 100-200
D 201-300
C 301-375
B 376-450
A 451-525
S1 526-600
S2 601-675
S3 676-750
R1 751-800
R2 801-850
R3 851-900
U1 901-950
U2 951-998
X999
While it looks complicated at first, it will provide more balanced competition within each class, especially if the PI system itself gets changed finally.