Sticky on the front, loose on the back?
 

I love the the combination of responsiveness and stiffness the BRZ has. But I feel like it has a bit too much understeer in the corners. I am trying to adjust the issue by putting on some sway bars, how should I look into all the options? How does the stiffness compared to OEM contributes to the cornering characteristics? Also, if one bar is 100% stiffer than OEM, what does it mean for the ride? Right now I don't have to worry too much about pot holes and speed humps as long as I am within reasonable speed. What happens with the 100% or even more stiffness?

What suspension do you have now? If all you want is more oversteer than just up the rear bar and leave the front alone for now.

Actually it sounds normal, these cars were designed and typically front planted rear less planted especially for track use. Sounds like you're braking too late going into the corners. just a thought

Hmm. On stock Primacies? Have thought about going other way around, eg. putting springs from FR-S? Though imho easiest/cheapest would be to play a bit with tyre pressure front/rear, and only then think about something to buy from aftermarket parts.

Add some front camber to start.

- Andy

^ is a good suggestion to start! And where are you running into understeer? Are you on a track? Or canyon driving? I never have understeer unless I brake too late into a corner like @stevesnj suggested.

Swaybars are for fine-tuning balance after you've done all the other things. Start with front camber, as Andy said (Camber bolts, $25). A decent performance alignment will do wonders.

Then consider tires. The OEM tires are ok, but they aren't great. It's easy to overdrive them, and if you ask more of them than they can give, you'll either get understeer or oversteer. They're great for learning because they're loud at the limit and they let go gradually, but regarding absolute traction, they're not that wonderful. A better tire will have better turn-in at better speeds.

Good question is where is the understeer observed. Corner entry or exit? During throttle or braking?

The car is very neutral and you can probably correct this for cheap or free by purchasing camber bolts, or adjusting tire pressure and driver input.

Check pressure often and make the rear slightly higher than the front.
Turn in just before completely releasing the brakes, to keep the nose planted and the tail light.

I definitely agree. I've personally NEVER had understeer on corner exit... but I could see how it could happen on some corners depending on elevation and geometry changes.

If you are on the stock susp and street cornering the best thing to do is take OUT the camber. Get rear arms and set it to .4, leave the fronts as is. I noticed this in my old RX-8, the factory settings made it feel horrible in the corners, with lots of roll at the back.

The fronts have ~0*, which is horrible for any sort of spirited driving. By leaving the fronts and reducing rear camber you're reducing overall grip. By adding front camber (more negative) and leaving the rear alone you're adding overall grip.

As for understeer, it's easy to induce if you enter too hot, doesn't have to be under braking. Getting understeer on exit is a bit harder to induce, but can be done.

Stiffer spring rate at the wheels = more load on that wheel. Stiffer front sways = more load on the front, and stiffer rear sways = more load on the rear.

When your load overcome's the tire's grip (ability to hold load), then the tire loses traction.

Start with your sways on full soft, and then if you still understeer, increase the rear sway by one setting. If you oversteer, increase the front sway by one setting.

Test at a safe environment; you don't want to be spinning out on the street if you get unexpected oversteer.

Go to the closest Subaru dealer and pick up the OEM Impreza crash bolts to dial in some more front camber (part #901000394). I think it's like $10-12 for the pair and pretty easily the best bang for the buck upgrade for a stock car.

Also you may just be into the throttle in the turn. Braking earlier and lightly in a corner let's momentum take you through the corner and then ease back into the throttle when you are just about out of the corner. Eventually you will start to learn when to brake later going into the turn and earlier accelerating out. I say work on this technique before putting out $$$$ you don't need to