I’ve used the FSDs with a variety of springs (and many other strut & spring combinations); the best spring is the stock spring for the FSD designed for the MINI model. To get the full benefit of the FSDs on the MINI they need as much travel as they can get and on the MINI that is very limited, up front especially. The Konis will still function with lowering springs but their unique effectiveness (the part that you are going to pay a premium for) will be diminished.
Lower is not always better especially if your roads are poor quality; there is a lot to be said for ground clearance. Lower does not mean less body roll without changing other aspects of the suspension geometry beyond struts. Alter suspension components one at a time and give yourself plenty of usage in a variety of conditions before moving on to the next change; wholesale changes may not give the desired results.
Installing struts is not a difficult task. The tools to perform the install will cost much less than a shop’s labor rate. There is nothing wrong with having a professional perform the install and in some cases that is the best option, but, the choice for having someone else to do the work or doing it yourself should not be based on “mystery”. Here is a how-to for installing springs and it’s valid for struts also
MINI COOPER :: North American Motoring - Springs Install How-To .
