FK lowering springs? Wheel spacer size?

A set of these have come up second hand for £50, 40mm drop and low mileage useage (apparently)

What are people's opinions on fk springs? Can't find any decent reviews on them.

I basically want my car to sit lower (obviously) but don't want to buy rubbish quality products.

Also what size spacers can you guys recommend for me as my car is a non-sport?

Thank you all
 
Don't know much on those springs but for the spacers, I've heard whatever you do to the front, do to the back. So if you have 25mm spacers at the front, don't put a different size at the rear else it may mess up handling. (Only what I've been told, I may be wrong)
 
Cool thanks guys.

I think I might give 20's a go when I get the money together...is that 20mm per side or 10mm per side so then it adds up to 20? I don't kniw how they market/sell them description wise.

Any spacers out there that are to be avoided?