If you are wanting to buy a set of lowering spring for you Ford focus the please read on
The front springs on the Focus are quite easy to do as long as you have a good set of spring clamps and some basic car maintence skill
Remove the front struts clamp down the springs and remove the nut at the top of the strut and remove the spring ,remove clamps slowy ,clamp down new spring and re-fit .
The big problem with fitting lowering springs or even new springs is when it comes to the rear .
Jack up you car at the rear as high as possible put axel stand at both side to make sure car is safe ,take of both rear wheels and you will see the rear springs .
Now you are very tempted to start undoing the lower suspension arm bolts but DONT .these bolts are prone to seizing into the bushes and will just brake and there a pig to try get out and you end up haveing to buy two new lower suspension arms at around £80 for 2 not to mention you have to spend time cutting the old bolts out and then you need new bolts also and once you car is back togther you need to get the rear camber checked and aligned
You have to try and get what ever spring clamps you have and clamp the springs down and pull them out ,if you handy with a welder and have some threaded bar about you can custom make some clamps to do the job , if you know a Ford mechanic ask if you can borrow his or get him to do it for you as ford have special clamps just for this job .
Once you do get your old springs out you need to clamp down your new ones and then put them back in and take the clamps off again
If you had the right tool is like a half hour job but if you dont it can turn into a nightmare
Even doing the front yourslef and take the rears to a ford garage if worth it just to save on hassel and they wont charge you any more than an hours labour
I cant stress how much hassle these rear spring can be if you dont do the job correctly , I took mine to a tyre and exhuast fitter who of course also fit supension parts and they had the car for 3 days the front took no time at all and the rear where just a nightmare becuase they started trying to undo bolts they did not need to touch ,the bolts broke and then i needed two new suspesnion arms ,i had to wait for parts coming in and got my car back 2 days later .
Hope this helps you avoid the hassle i had .