Originally Posted by Jub

I've had an 03 and an 06 that I've autocrossed a bit. I definitely thought the AP1 was more "playful" though I think I finally got my AP2 to rotate similarly under throttle. The AP1's rear roll stiffness was noticeably higher, contributing to it being more playful. I can't comment how much is attributed to increased rear roll stiffness versus the toe change. I've never had an AP1 with same spring rates as the AP2 or vice versa. Presumably, both spring rate and dynamic toe play a role in the handling differences. The one thing I've noticed, that I think is highly attributed to the toe change, is that the AP2 is less nervous under braking. The AP1 transitioned quicker and was more adjustable on the limit, IMO, mostly because of the stiffer springs.

To the point of the original post... For a street car, I don't think the toe changes are very consequential. Go out, get a good alignment, and be happy. There are plenty of threads on AP1 alignments and it has been beaten to death. I won't beat that horse here. I do not believe that many, if any, wrecks on the street due to "snap oversteer" and "dynamic toe change" would have been saved had the car been equipped with one of the toe-kits. Driver error accounts for 99.999% of them. The things that caused my AP1 to spin would also cause my AP2 to spin 99% of the time. Most driver errors are pretty egregious and the S2k is pretty sensitive to them, regardless of AP1 or AP2. Lifting off the throttle while turning in quickly will cause the car to spin regardless of AP1 or AP2. There is a noticeable difference between the two at the limit but most people who wrecked were going to wreck anyways. I'd guess that most of them would "snap-oversteer" just the same in a camry, had they entered the turn fast enough and lifted the throttle aggressively while turning in.

I think that the aftermarket toe kits should be used only with the understanding that they are not an OEM part and have not been subject to the extensive testing and quality control that OEM parts are subject to. Therefore, you should be inspecting them and replacing them accordingly. I do not think they fit the average person's needs on a street car and would argue that they introduce more risk than they mitigate. There are a few threads and accounts of them breaking. The mode of failure would be pretty ugly on a public road. I'm glad they're offered and I think they have a purpose on track cars but not street cars. If you feel the need to address the toe change, I am on the side of swapping in the AP2 rear components. As of now, they are probably sourced pretty easily and on the cheap. I'd imagine that in the next few years, they become much harder to get as less and less of these cars are being parted out. With the OEM AP2 components, you remove most of the dynamic rear toe change conditions while using highly tested, reliable parts, that should not fail under normal circumstances.