Bought a stock MY00 about 2 years ago, and left it stock the whole time save for an AP2 rear sway. The car was tail-happy as could be, but I learned to love it's propensity for oversteer, especially on corner entry.
However, due to some recent mods the car is under steering on corner entry, and it's extremely frustrating.

Recently I came across a stupid deal on some ~30k Koni yellows for $80 and put some Swift Spec-R springs on. I also installed the Megan rear bumpsteer correction kit, since my OEM toe arms had worn ball joints, and I'd heard nothing but praise regarding the Megan kit. Also went from AP1 wheels (RE760 Sport) to AP2 wheels (Continentals Extreme Contact Sport).

TLDR
Use: Very spirited mountain driving (Deals Gap, The Snake, NC80, etc)
How to fix my corner entry understeer?
AP2 wheels 215/245 Conti ECS
Stock MY00 sways
Koni w/Swift Spec-R (7.5k/7k)
Megan rear bump steer kit w/smallest spacer
Front 0 toe, -1.8 camber
Rear 0.12 IN TOTAL, -2.2 camber

Possible solutions:

I'd LOVE to go to a square setup, but I'm presently waiting for a deal to come up. Guessing that would solve my issue without changing anything else?

Try swapping front 7.5k springs onto the rear? I'm doubtful that 0.5kg is going to make a drastic difference.

Try a softer front sway?

Reduce the rear toe?

My last suspicion is that the Megan BSK kit is neutering the handling by getting rid of the dynamic toe steer, and that switching back to OEM toe arms would bring back some of the car's tail-happy traits?

Open to input!

 

 

Your car is already set up well for square. I'd make the leap when you find a good deal. I'm not familiar on your Kono setup, but if you can soften the front and stiffen the rear it could help remedy in the meantime.

 

Moar front camber
Less rear toe

 

The rear toe arm BSK is just stabilizing the amount of rear toe change.

Maybe try running close to 0 rear toe. But 0.12 deg total is pretty dang low already.

Nothing points to excessive understeer.

Maybe try driving differently? It could also be the new tires/sizing.

 

Hmmm, I read 0.12 IN as 0.12 inches (or 0.28°). Agree that 0.12° total toe-in is low enough...

 

aside from trying the cheapest easiest things first,

-more negative front camber
-maybe swap springs
-maybe softer front sway
-maybe less tire pressure in front

...maybe some stickier tires in 225 like re71r or rs4 and driver adjustment. too much understeer on corner entry perhaps asking too much of your current front tires for what they are (conti ecs), braking/turning at the same time? just some thoughts.

 

Have you tried refitting ap2 rear sway bar

 

Had an 02. If the konis are adjustable. 1/4 turn for full stiff in the front. 1/4 furn from full soft in the rear. Get an CR front sway bar to stiffen up the front. Square set up is a must with 255-40-17 sticky 200. -1.6 front camber with .01 total toe and max the caster too. Rear -2.0 with the same toe. This will wear the tires evenly across them. Best of luck and enjoy. Track day to learn the car is a big help to.

 

I think a stiffer front sway bar would make the understeer worse with staggered size. Typically people add a front swaybar to reduce AP1 oversteer tendency, but then add front tire width to bring the handling back to neutral with incerased limit. You will want a bigger front swaybar for square tire size. As mentioned max out your front camber if you haven't already

S2000s are known for low speed understeer and it sounds like you've modified and pushed the car to the level where your staggered tire size is hurting you in those low speeds, assuming this NC80 is similarly low speed like 129.