USA Prius Handling changes?

First, let me introduce myself. I have been driving small sports cars for about 20 years now. I am active with the SCCA, and have competed in Solo2 events for about 10 years. Currently I instruct SCCA Solo2 driving schools in my spare time. I am a Skip Barber racing school graduate, and currently race 125cc shifter karts. I have previously race Miatas and Volkswagens. I'm including all this information to say that I have enough background in performance driving to have a clue about handling.

I had been shopping for a Prius for about a year before I bought one. I test drove an early 2004 in Boulder Colorado, and was pretty disappointed in the handling. I thought the car was downright scarry at highway speeds. Turn in was sloppy, and it kind of wallowed in turns. The rest of the car was pretty impressive, and the drivetrain was about as fast as my Miata. My thought was that handling was easy to fix and the rest of the car was great, so I would keep an eye out for a chance to buy one.

Around the end of 2004 the supply began to loosen up and I was able to buy one with only a 2 week wait and a little under list price. When I picked up the car in January 2005, I thought that my memory must have gotten soft regarding the car's handling. True, it still didn't handle like my A4, but the car's handling was way better than I remembered. It doesn't wander at all on the highway, cornering is acceptable, and I really enjoy driving it.

I can't imagine that all this is because of alignment (although highway stability could be affected). Is it possible that an early 2005 would have a slightly tweaked suspension compared to the 2004s? Are suspension parts source from multiple suppliers and it's the luck of the draw which one you get? Anyone out there have a guess?

Also, I've scoured the web looking for any upgraded suspension parts. I've found some in Japan, but was hoping for some in the USA. Anyone have any luck with springs, shocks, or sway bars. Or.. does the Prius share any suspension components with other Toyotas? ... perhaps some performance parts for a Camry or Corolla might fit?

 

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I see nothing there but some chassis braces.

 

Perhaps because they haven't been able to find parts. I think the car would benefit from slightly firmer springs, stiffer sway bars, and increased shock damping. The parts are available in japan.