Can I fix understeer without killing ride quality?
 

I use my car as a DD with a autocross thrown in about once a month. The roads where I live suck and right now I'm really impressed with how well the stock suspension handles it. I don't want to lose that quality, and turn this thing into a buckboard just to make it handle better at the track. I understand to fix the understeer I can increase front camber (reduced tire life), increase front spring rate (harsher ride), stiffer rear swaybar (harsher rough road ride). I believe my best option would be to replace just the rear sway bar with a slightly stiffer one (+15 to 20%), but I have limited information on them. I think the Stillen bars are the softest out there but the rear alone might be too much of a jump from stock even at the softest setting. Are the better rear swaybar options out there (Nissmo maybe)? I can't have this thing tail happy either. Will adding the Stillen's front and rear bars get me to neutral handling without making my car less enjoyable on my day to day crappy roads? I can live with some body lean but not the understeer. It would also be nice if the fix was cost effective too. Lowering the car is definitely not a option. My car's a 2010 hardtop with the sport package and I usually drive with the VDC "off" 99% of the time. (I'm old school)

Try the Stillen sways and see how they work out for you.

A little bit more negative camber up front will help with understeer as well, but you will definitely change the factory tire wear characteristics if you do that.

Just get a bigger front tire, you will fix most of your understeer. As far as ride, the RE11 is a nice autox tire that rides better than stock. Toyo RA1 and R888 also ride better, but they emit a lot more noise (265 or 275 or 285 all around)