Hi Kritho, Welcome to the Forums
The Kings SL springs as listed should be fine as they are designed to fit from 2005 onwards ... As far as an exhaust system to suit is concerned, I would suggest you read through some of the other posts in the Focus section as there are quite a few different systems to choose from, a lot depends on what you're after, how much you want to spend, how loud you want it etc.... any good exhaust place should be able to give you advice on the different systems available