Czesc! Tez jestem Polakiem.
Anyway... The D2 coilovers are very nice. They used to be available for around $800 when they first came out, and they haven't changed much. They're top quality though and I've heard very good things about them. I wanted to get a set myself until the price went up.
The KW suspension is nice, the tube is stainless steel I think compared to anodized aluminum on the D2's... The KW's are probably a little heavier. There's a pillowball mount on the D2's though and I don't think the KW's have that.
For the front and rear strut bars... I had the DC and I sold them (the polished aluminum ones which are multiple piece). The front DC strut bar isn't bad actually, it worked well for me. I just got into the JDM (Japanese Domestic Market) thing, so I ended up buying the Spoon. The Skunk2 bars are nice, I would get those over the DC ones. Or... Carbing. Or... Mugen. Mugen are expensive though.
In Poland the roads do suck. Depends on where you live though. Near big cities like Warsaw and Krakow and Lodz and Lublin and Gdansk the roads are OK. In other places you're talking about rallying instead of being on a road. hehe...
All in all though I would say that an aftermarket suspension is a good thing. It's how much you lower that's important.
Also... If you're going for 17" wheels, you could go with a larger profile tire to raise your car up a little. Then you can lower it more and fill out the wheel wells while not having the car sit too low. Its an option.
