How to achieve flatter cornering?

The real benefit difference will be noticed with lowering springs. Since you don't want an overly stiff vehicle, you might want to start off with a rear sway bar first. Look at wheels and tires second. Third look at strut tower brace or at lowering springs.

Look to do the under body braces last.

 

Sway bars will keep your car flatter through curves and turns by resisting body roll. You already have one in front, a couple are available for the rear.

Front and mid chassis braces are available as well, along with the strut tower braces. These stiffen the chassis and make the car feel more planted and less squirrelly as well.

SCH-I535

 

Read somewhere that greatest benefit to handling is achieved with rear sway bar first, then lowering springs.

Of course getting a wheel and tire that gives you less side wall to flex, going +1 to +2 on rim diameter will benefit handling as well, but comes at a fuel economy penalty.

SCH-I535

 

Rear sway bar and lowering springs.

SCH-I535

 

If you don't want to go the wheel/tire route I would recommend: Rear Sways + Strut Tower Brace. Make your assessment if you still need to improve and go with underbody bracing before you do springs.

 

It makes a big different in turning, it's flat, tight and sharper turn, plus the rear sway bar from the plus package also improve the turning with less body roll, I am just like you don't want to lower the spring, overall I am pretty happy with the combination of Cusco strut tower bar and the "Plus" rear sway bar. I can drive fast and able to handle well only 1 thumb on the steering wheel at or over 80 mph+. I am using stock 15" tires and the tire pressure set at OEM standard 35 front and 33 back. It will make the Prius more fun to drive after the add on, the car feel more solid and stable on or off freeway speed, definitely you can notice chassis stiffness. hope this can help.

 

Great conversation and wished I had asked the same questions. I have the TRD "Prius Plus" lowering springs and rear sway bar already purchased, to be installed next week. The Prius Plus forged 17" wheels go on next. I also just spent the extra cash in the latest generation Rude person's "lightweight" and "bulletproof" front chassis brace.

No strut bar...

Will my set up be overkill? Any downsides? Do I go all out and get the strut bar to complete the package?

 

The TRD plus lower spring and rear sway bar without the TRD forge wheels will make the car run ok you will notice less bouncing, firmer ride but may not improve the handling unless you add the strut tower bar and the 17" wheels and tires, now...when you start tear apart the front suspension why not at the same time add that strut tower bar on since you HAVE to remove the windshield wiper assembly and the metal tray, so that you don't have to do that again when you add the strut tower bar later on (I highly recommend the Cusco strut tower bar). I personally don't like the underbrace add on and I have had 2 different unit installed and removed, (Tanabe and Ultra brace) it makes the ride too harsh, stiff and feel like no suspension even with the stock spring. This is just my personal experience so don't take it seriously.

I have a coworker bought a 2012 PIP and add the TRD plus spring, sway bar and the 17" forge wheels with Michelin tires, but he doesn't have any under brace or strut tower bar. I rode in his pimped out PIP and really like the ride quality, no rough ride, the turn in are GREAT and I like it, just it's too much $$$ to burn.

I went with my current setup just strut tower bar and the TRD rear sway bar, everything kept stock (I want to keep my MPG over 50+), I really like the way how the Prius perform, no rough ride, making turn so effortless with 1 hand, freeway drive much much more stable, my daily commute close to 180 miles and I have fun driving it, very close to my coworker's pimped out PIP. My setup cost a lot less compare to purchasing the TRD plus add on. This is just my personal opinion and driving style.

If you have extra $$$ budget and would like to pimp out the Prius, you will have a kick axx look and performance ride. Have fun modding the ride.

 

A rear sway will make a huge difference. Springs will add to that.

Personally, I found the mid-brace to improve the cornering quite a bit.