It actually not my best example,...but it would be the BMW M3,....with 50/50 weight, 53/47ish springs and matched damping, 50/50 ARB, and the slight bias of rear tire width, I feel that the car is almost perfectly balanced. I think mine also has low aero settings(2:3 ratio), but that isn't alot. It's everything together as a package obviously. In this case, the 53/47 spring bias accentuates the rear ARB and weakens the front. This serves two purposes, it promotes mechanical steering grip, and also corner exit acceleration grip/geometry.
A 45/55 RWD chassis I think would be the best performing car, but I haven't pursued the idea.
(Curiously,....911's have similar ARB and spring bias ratio characteristics but with a totally different weight distribution,....the reason being a major breakthrough for me in relating real world values and chassis balance to forza values. All the other chassis weight distributions are completely different btw)
The tire width and aero of the BMW keep the rear planted, and I can still tune the diff, brakes, and gearing around the remaining grip.
ALL street cars, regardless of "sportiness", are designed to understeer to some degree. Whether it be through ARB, damping, or other alignments or chassis/drivetrain characteristics, all street cars are designed to default into passive understeer state. Obviously, outside influences and driver inputs can overcome that understeer, but its still predominantly there.
Even full blown race cars when properly setup tend to favor a slight on throttle understeer condition. Mostly because ease of driving and predictability equates to speed.
Now a car like your Mazda Open2nd has a slightly different setup. The tire widths are a little different, I don't remember it having aero, and I am unfamiliar with your other brake and suspension settings. I would suspect that you are running softer rear springs,....but if you are also running a stiff front ARB then you are probably rebiasing the chassis via the dampers. More specifically very low rear rebound, and somewhat high fronts. I can only guess though based on what your comments have been.
As for basing "real world" relationships on in game cars,....i'd be very careful not to read into it too much. I am personally at fault for trying to relate what I know about modern VW/Audi/Porsche suspension components and suspension dynamics, but I now try to take what I know as only a reference for ideas, not absolutes.
In the game we tend to over bias spring values, and by doing so generally need to rebalance the cars with other settings. Also keep in mind that forza uses the same generic suspension model and geometry for all four corners of every car.
If memory serves correctly I think the real world FC RX7 uses front struts and some pretty advanced dynamic alignment settings similar to modern 911s in its independent rear.
As far as IRL aftermarket bars are concerned, remember that diameter is only one aspect of tersional resistance. ARB's can be connected at different points on a suspension geometry which alters the roll resistance. The length of the ARB arm from front-to-rear to the chassis mount can also affect torsional resistance. The amount of anti-roll is directly tied to spring strength as well. The stronger the springs the greater the torsional resistance needed to maintain the same anti-roll.
Regardless, consistency and stability of handling isn't as important in a game as it is IRL, so tuning closer to the balance of a car can extract a little potential.
I'd like to tune your cars guys, Caseys RX7 and Fits CTS-V, just to see what you think. I just need the weight, tire widths, aero values(if any), and weight distribution. I assume they are both RWD.
I'll buy em, or you can gift copies too, if you want, or you can keep the builds and tunes to yourselves too, i'd just like to throw my latest calcs at em and see what you guys have for feedback.
