The Eibach Pro Kit was actually designed for use on the early AP1's, and your AP2 is quite different. I have a Pro Kit on my MY00 car and the changes to the stock handling were minimal, certainly much less than the difference between the handling of a stock MY00 car and a stock MY05 car like yours. Since the springs weren't actually designed for your car you might want to consider replacing them with stock springs.

However, your tires and alignment are probably also contributing to the problems you're experiencing, and on top of that, the "problem" could simply be that you need some time to adjust to the cars quick handling. Most of us require a period of adjustment.

Do get correct tires on the car! The wrong tires can make the car unstable and unsafe.
Do get the car aligned after the new tires are installed.
Consider getting a set of OEM springs to replace that Pro Kit. It's not designed for your MY car.

 

 

My car felt twitchy and unplanted especially in the rear before the alignment after the drop with the S. Techs. Get the alignment first and foremost you will notice a difference. Mine now handles at least as good as stock.

 

While it was not related to the lowering, we accidently go the rear toe on my car set too close to zero, and the handling at speed was downright scary. Alignment on this car is quite critical.

Same goes for tires and tire pressures.

HOWEVER, the Pro Kit spring rates are just WRONG for an AP2.
They may not totally trash the cars handling (I'm not really sure), but they are certain to reduce stability.

I think this is the sum of a number of issues, all of which need to be resolved to get the car to handle properly.

 

Yes, what RED said, tire pressures, make sure your local tire shop didn't put them too high. I took my RE050a's to get mounted at my local shop, the guy tried to put my tires at 40psi !!!!!

 

If the car is lowered it must be re-aligned. I doubt it ever was. Lowering the car changes the suspension geometry.

Also, does it transition between oversteer and understeer without you doing anything or does it switch between them depending on throttle and brake?

If your steering wheel is actually tilted an alignment won't fix it but a frame machine might. Was the car ever wrecked? Did you get a carfax on it before you bought it?

Tire advice above is also good. And some of the instability may be tramming depending on how "not perfect" the roads are in those curves. This is when the wide aspect tires tend to make the car follow road imperfections.

 

PS: Care looks GORGEOUS!

 

what is the right amount of PSI should my tires have?? does it have to be the same PSI for all four tires??

 

it's in the manual, it's in search, it's everywhere if you did a search.

32psi cold all four corner.

that's a good starter number for stock car in the street, on the track you can play around with it more, FYI the rear i run 34-35psi vs 32 front