I've seen a lot of Foci using Eibach. Their one kit that drops like 1.6" looks good with 17's tucked under it. I have an 05 ZX5 and leaning between Eibach and Voitland. Just search around and compare kits. Go with what you like and testimonials. Just don't do it the cheap way (just springs). Spend the extra money and get everything. Struts, shocks, springs, dampers, etc. Good Luck and post some pics when you get it done.
I have tried both Eibach (Pro Kit) and Vogtland. I like the Vogtland better. I have them with a set of AGX gas shocks. I find the ride with the Vogtland to be better and I get better response from my car with them also. The Eibach were good and are not a bad choice. I just like the Vogtland more. I found them on Ebay with the AGX shocks for $465.00.
Its a question of money and what you're looking to do...you can easily drop a thousand or two on suspension (with coilovers/airbags), but there's several issues you have to take into consideration; such as how many miles do you put on the car, how are the general road conditions in your area, and do you race the car at all, either on the weekends or a more serious setting? I'd suggest the SVT kit, its only ~$250 for the SVT springs, struts and dampers and rear roll bar. Plus its able to stand up to the sometimes horrific road conditions here in the 'states for many many miles...a high-dollar coilover kit or even high-end regular setup might wear out quickly if the car is daily-driven on bad roads.
Something else to keep in mind with a drop is the further you drop the car, the worse the ride quality is going to become. Plus you run the risk of prematurely wearing the suspension out if you frequently bottom out, and you could damage components under your car (like the exhaust) by hitting them on speed bumps. Again, the SVT kit drops the car but not by a whole lot, it looks much better but the tires aren't tucked up inside the wheel wells.