Have you tried a set of extremes on this car, or any car yet? Before you install any suspension piece, its best you explore the limits of grip in factory settings first.
There are several benefits to doing this even with the standard size tires, before going crazy with alignment changes and larger wheel/tire sizes.
For one. Most of the extremes have larger tread blocks, which not only establish a higher level of contact patch for the same size, but wear in a much more uniform fashion. With this you can clearly gauge how much and where the tires are wearing most. There is no point of adding additional camber if you can't accurately use all of the available rubber on standard sizes.
In motorcycle terms, you've probably heard this banter called "chicken strips" on the tires. Similar lack of wear lines can be established on normal car tires. gauging these wear lines give you an idea of how the camber is effecting tire contact patch and also how much steering input you are putting in and where in relations to corner loads and throttle modulation.
Another form of measurement you'd should start implementing immediately if you don't already, is measuring tire pressures and heat margins across the tires. A cheap harbor freight of homedepot infrared gun can gauge heat across the tire accurate enough to tell you how much heat you are balancing across the tread. In these summer conditions you may find it easy to go from a cold 35psi to hot 41 psi in a relatively short spirited run, but getting temps up in colder conditions is equally important.
For the sake of understanding what you are feeling, its good to also randomly test different tire pressures so you know what overinflated tires feel like compared to under inflated. The gas station air pump should be your new best friend.
You have several back roads i'm sure you take advantage of already. But instead of trying to go outright fast or pushing the limits. Push the limits in different ways. Form a solid pace and intentionally try to induce understeer and oversteer by playing around with your steering input speeds as well how early or how late you enter a corner with modulation of braking a acceleration. Measure the tires accordingly after each run. You may say this is stupid or unsafe, but this is the point of establishing a slower overall speed.
Practice makes perfect, build up the aggression gradually
